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DESIGNING QUALITY LEARNING SPACES

Indoor Air Quality and Thermal Comfort

Version 1.0, September 2017

Copyright 2017 Ministry of Education

Document history

The table below is a record of the changes that have been made to this document:

Revision date Version Summary of changes

September 2017 1.0 First version for general release:

amalgamates two 2007 Designing Quality Learning Space guidelines – Heating and Insulation, and Ventilation and Indoor Air Quality

substantial changes to content to reflect current teaching practise and flexible learning space design

document rewritten for a target audience of architects, designers and engineers involved in the design and specification of schools

Ministry requirements are now clearly marked as ‘mandatory’ or ‘recommendation’ to make them easy to find throughout the document.

Foreword

This document aims to ensure that the indoor air quality and thermal comfort of school buildings

supports quality educational outcomes. It does this by setting minimum requirements and

recommendations that must be considered when building or upgrading school buildings.

This document replaces two 2007 Designing Quality Learning Spaces (DQLS) guides: Heating and

Insulation, and Indoor Air Quality.

All projects that commence after 1 January 2018 must meet the DQLS – Indoor Air Quality and

Thermal Comfort requirements.

Background

The Ministry of Education (the Ministry) owns one of the largest property portfolios in New Zealand,

with more than 30,000 buildings in approximately 2,100 schools.

The way teachers and learners engage with each other has changed significantly in the last decade.

School design needs to reflect the changing needs of the users, and learning spaces must be

designed to support the way they are being used.

The DQLS series of guidelines were first released in partnership with the Building Research

Association of New Zealand (BRANZ) in 2007. The update of the DQLS series has been undertaken

to ensure the spaces that are built can support the many different styles of teaching and learning.

There have been substantial changes made in this update.

Indoor Air Quality and Thermal Comfort

Indoor air quality and thermal comfort have a direct impact on the usability of the space and on

learning outcomes. The technical guidance in this document has been developed from the latest

research and the review of school designs undertaken by the Ministry’s Design Review Panel.

Acknowledgement

The Ministry gratefully acknowledges the assistance of eCubed Building Workshop, the Ministry’s

Design Review Panel members and BRANZ in creating this document.

Feedback and updates

We are seeking to constantly improve the content and usability of our guidelines. If anything in this

guideline requires clarification please contact the Ministry through [email protected].

Your feedback will help us to ensure this document is maintained as a valuable resource for all of

those involved in the design of our schools as effective learning environments.

Kim Shannon

Head of Education Infrastructure Service

mailto:[email protected]

Contents

Introduction .......................................................................................................................................... 1

1 Requirements and Recommendations.................................................................................... 7

1.1 Indoor air quality and minimum fresh air ventilation requirements ........................................................7

1.2 Performance requirements .................................................................................................................................8

1.3 Ventilation design strategies ............................................................................................................................ 12

1.4 Indoor temperature levels, stability and control ......................................................................................... 13

1.5 Provisions for teacher monitoring and control of environmental conditions ..................................... 21

2 New Buildings .......................................................................................................................... 25

2.1 Introduction ............................................................................................................................................................ 25

2.2 Integrated passive design approach.............................................................................................................. 25

2.3 Building form ......................................................................................................................................................... 31

2.4 Orientation.............................................................................................................................................................. 31

2.5 Window to wall ratio, glazing and shading................................................................................................... 32

2.6 Thermal insulation ............................................................................................................................................... 33

2.7 Thermal mass ....................................................................................................................................................... 36

2.8 Pollutant control.................................................................................................................................................... 36

2.9 Ventilation design ................................................................................................................................................ 38

2.10 Natural ventilation strategies ............................................................................................................................ 41

2.11 Thermal comfort ................................................................................................................................................... 49

2.12 Design tools ........................................................................................................................................................... 51

3 Upgrading Existing Buildings ................................................................................................ 53

3.1 Indoor air quality ................................................................................................................................................... 54

3.2 Ventilation design ................................................................................................................................................ 56

3.3 Thermal insulation ............................................................................................................................................... 56

3.4 Thermal comfort ................................................................................................................................................... 57

4 Specialist Learning and Ancillary Spaces ............................................................................ 59

4.1 Halls and multipurpose spaces ....................................................................................................................... 59

4.2 Gymnasiums ......................................................................................................................................................... 62

4.3 Libraries .................................................................................................................................................................. 64

4.4 Music facilities ....................................................................................................................................................... 66

4.5 Science and technology spaces ..................................................................................................................... 68

4.6 Workshop technology spaces .......................................................................................................................... 70

4.7 Science spaces .................................................................................................................................................... 72

4.8 Server rooms and IT equipment cupboards ................................................................................................ 74

4.9 Toilets ...................................................................................................................................................................... 75

5 Components, Systems and Strategies.................................................................................. 76

5.1 Thermal performance of construction materials ........................................................................................ 76

5.2 VOC content and formaldehyde...................................................................................................................... 76

5.3 Window ventilation effectiveness .................................................................................................................... 77

5.4 Proprietary ventilation devices ........................................................................................................................ 77

5.5 Active heating/cooling systems ....................................................................................................................... 85

5.6 Building control systems .................................................................................................................................... 97

5.7 Lifecycle cost ......................................................................................................................................................... 97

5.8 Safety in design .................................................................................................................................................. 100

6 Glossary and References ..................................................................................................... 103

6.1 Glossary ................................................................................................................................................................ 103

6.2 Tables .................................................................................................................................................................... 109

6.3 Figures .................................................................................................................................................................. 109

6.4 References ........................................................................................................................................................... 111

Designing Quality Learning Spaces – Indoor Air Quality and Thermal Comfort 1

Introduction

Purpose

This document provides technical requirements and guidelines for the indoor air quality and thermal

comfort of school buildings in New Zealand. It provides guidance for design teams to plan and specify

fit-for-purpose schools, which may include the provision of new flexible learning spaces (FLS) that

support the creation of innovative learning environments (ILE) for schools to deliver the New Zealand

Curriculum and Te Marautanga o Aotearoa.

The principle focus of this new guideline is to outline new minimum requirements and

recommendations for indoor air quality and thermal comfort, and explain in detail the various factors to

consider to meet these requirements.

Intended audience

The DQLS series of guidelines are written for architects, designers and engineers involved in the

design and specification of New Zealand schools. They also provide relevant technical guidance for

property managers undertaking school projects.

The DQLS guidelines are also to be referred to by property professionals for the purpose of:

briefing design teams

informing and reviewing designs and specifications

estimating costs

undertaking Technical Post Occupancy Evaluations.

The DQLS guidelines set the performance requirements for new schools and the benchmark for

upgrading existing schools. The values given are intended to maximise the utility and flexibility of

learning spaces for all users. The guidelines aim to promote inclusive design and take into account the

general range of abilities and learning support needs expected to be found in New Zealand schools.

Learners with specific learning support needs may require provisions in addition to the requirements

set in the DQLS guideline series.

How to use this guideline

This document aims to be comprehensive in its guidance. For first time users, we recommend you

read all sections fully to get a broad overview.

When working on a specific project, we recommend the architect and heating and ventilation

engineers read Section 1 and Section 2 (in the case of new build projects), or Section 1 and Section 3

(in the case of upgrade projects).

If your project contains specialist learning spaces, gymnasiums, halls, libraries, and/or administration

spaces, then you will also need to read Section 4 to gain more specific guidance.

Section 5 provides detailed guidelines to assist heating and ventilation engineers in carrying out

system design and analysis. In addition to providing information on the heating and ventilation

performance of particular components and systems, Section 5 also provides guidance on lifecycle

costing and safety in design considerations.

http://www.education.govt.nz/school/property/state-schools/design-standards/flexible-learning-spaces/http://ile.education.govt.nz/

2 Designing Quality Learning Spaces – Indoor Air Quality and Thermal Comfort

Document hierarchy

The Ministry is committed to providing quality learning spaces to enable education and learning in

schools to achieve the objectives of the Education Act 1989.

The Designing Schools in New Zealand (DSNZ) document is the overarching guidance for school

design. It states the Ministry’s policies for schools, the project design process and general principles to

be applied during planning and design. The DQLS guidelines support the DSNZ by providing detailed

performance requirements for refurbishing and creating new school buildings.

http://www.education.govt.nz/school/property/state-schools/design-standards/education-infrastructure-design-guidance-documents/


Indoor air quality, thermal comfort and learning

School aged children have greater susceptibility to some environmental pollutants than adults

because they breathe higher volumes of air relative to their body weight, and their body tissue and

organs are actively growing. Children also spend more time in school than in any other environment

except home. Indoor air quality is dependent on the concentrations of CO2 and other respiration

derived pollutants, volatile organic compounds (VOC), particulate matter and other pollutants such as

formaldehyde.

The primary strategies for maintaining good indoor air quality are:

providing suitable ventilation with clean fresh air

selecting low VOC building materials; maintaining a good cleaning programme, and

using entry/exit mats to capture dust and dirt before they are brought into the building.

Children are also more sensitive to higher temperatures than adults, and they generally prefer

conditions to be a few degrees cooler due to their higher metabolic rates and higher activity levels

over the course of a school day.

In reality, what feels comfortable is not just related to air temperature, but also to relative humidity,

surrounding radiant temperatures, air movement, occupant activity levels and clothing worn. ‘Comfort’

inside naturally ventilated buildings has been found to be related to the prevailing outdoor

temperature, and in particular to the running average external temperature experienced in the

preceding few days. Comfort expectations of staff and students will adapt accordingly to this

experience of external temperature.

Figure 0.1 The connection between physical health, cognitive and mental well-being, and long-term academic

achievement (Credit: derived from the Schools for Health Program, Harvard T.H. Chan School of Public

Health).

Importance of indoor air quality and thermal comfort

The previous DQLS – Ventilation and Indoor Air Quality (2007) guidelines note that:

“Based on a survey carried out for the Ministry of Education by AC Neilson, teachers felt

ventilation and airflow was critical overall and that these were closely linked to their ability

to maintain control over the temperature in classrooms. Students also rated good

ventilation, along with having rooms that were not too hot or too cold, as important in

helping them to learn.”

Feeling

well

Biological and

physical health

Thinking

well

Short-term

cognitive and

mental wellbeing

Performing

well

Long-term

academic

success and

achievement


A recent multi-level analysis of 153 classrooms in 27 primary schools in the UK, by Barrett et al.

(2015) identified the impact of physical classroom features on the academic progress of the 3,766

pupils who occupied those spaces. It identified seven key design parameters that together explain

16% of the variation in students’ academic progress. These design parameters were light,

temperature, air quality, ownership, flexibility, complexity and colour.

Figure 0.2 Relative contribution of key classroom design parameters to academic progress (Credit: derived from

Barrett et al., 2015).

Of the 16%, a third of the variation was due to indoor temperature and air quality.

Some of the principal findings of the study related to indoor temperature and air quality include:

unwanted sun heat is a problem where external shading is absent

large window size is not universally valuable in terms of students’ learning outcomes. Orientation,

shading control (internal and external), the size and positioning of windows all have to be taken

into account so that the risks of glare, over-heating and poor air quality can be avoided at the

design stage

students perform better where temperature control is easy

factors that affect CO2 concentrations are correlated with learning progress

students perform better in teaching spaces that have mechanical ventilation, large volume or large

opening windows.

The study also supports inside-out design that builds from a focus on user needs, and challenges the

visual dominance of much design effort.

Adapting to different teaching methods

The 2007 DQLS guidelines were focused on the traditional aspects of heating, insulation and natural

ventilation. These old guidelines were prepared when classrooms were more simple shapes with

shallower plan dimensions, and characterised by more structured and uniform occupation patterns.

Flexibility11%

Air Quality16%

Temperature12%

Ownership17%

Colour12%

Complexity11%

Light21%

Design parameters contributing to a

16% variation in academicprogress


New schools are being designed with flexible learning spaces to enable innovative learning

environments, supporting a broader range of student learning needs and teaching practice. Flexible

learning spaces have different requirements in terms of environmental control due to their occupancy

patterns and flexibility. Deeper plans and lower ratios of perimeter wall area to floor area also change

ventilation and temperature control solutions. Occupation of large flexible learning spaces is generally

less uniform, with teacher and student use varying considerably both spatially and temporally, and

from inside to outside.

New buildings are being built better in terms of weathertightness, insulation and glazing standards.

Also in the last decade, a greater awareness of sustainable design and construction has resulted in a

focus on higher standards of indoor environmental quality, wellness and energy efficiency, and

greenhouse gas emissions.

In these new learning spaces design solutions for suitable thermal environments has switched from

needing heating to being at risk of overheating and from ventilation that works in summer only to year-

round ventilation. Designers are having to meet these new requirements whilst managing lifecycle

costs and environmental impacts.

Figure 0.3 An example of a flexible learning space. Multiple learning activities are taking place in different areas

with varying occupant numbers throughout the space.

DQLS Indoor Air Quality and Thermal Comfort - Overview

The DQLS - Indoor Air Quality and Thermal Comfort guidelines have been developed to set the

minimum standard for school buildings. Getting the indoor environment right is fundamental to

enabling students and teachers to be comfortable in their learning spaces. Providing good ventilation

rates and thermal control in learning spaces has been shown to support improved educational

outcomes and academic results.

In addition to the minimum requirements expected by the Ministry, this guideline offers best practice

recommendations intended to help users in setting priorities and making design decisions. A sample

of these requirements are:

occupied learning spaces are expected to have adequate ventilation to provide a minimum indoor

air quality range of 1000-1500 ppm CO2 (or less) over the course of the school day

indoor air temperatures within occupied learning spaces are expected to be within a range of 18˚C

to 25˚C for the majority of the year


the lifecycle cost of plant and services providing appropriate air quality and thermal comfort are to

be resolved at the design stage, to enable good investment decisions to be made

teaching staff and students should be able to respond to internal air quality and temperature

information to manage their own internal environment.

Within this guideline:

Ministry requirements and key information are in RED, look for the symbol on pages where there

are mandatory requirements.

Ministry recommendations and other key concepts are in BLUE, look for the symbol on pages

where there are recommendations.

Integrated design philosophy

Designers are to apply an integrated design approach to the design of schools and learning spaces.

The usability of a space, acoustics, ventilation, daylight and energy use are interrelated and a change

to one factor often impacts other factors.

Figure 0.4 An integrated design approach is required to ensure quality learning spaces are optimised over all five

environmental parameters.

While all environmental factors need to be optimised, the following hierarchy is essential when making

value engineering decisions to meet the available budget for upgrades to existing buildings:

Usability of space > Acoustics > Ventilation > Daylight > Energy Use

For new buildings, the Ministry’s performance requirements must be met. For upgrades or

redevelopments, as near to the guidelines as reasonably practicable is expected.

A major upgrade would be expected to meet all or most of the requirements and recommendations,

whereas a minor upgrade should target specific requirements and recommendations where the works

involved are practically capable of achieving them.

Designing for good air quality with suitable thermal comfort will provide well ventilated buildings with

comfortable learning spaces.

-

3

7

Daylight

Usability of space

Ventilation (natural/mechanical)

Energy use (heating/cooling)

Acoustics

Optimising learning spaces


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1 Requirements and Recommendations

The following section quantifies the Ministry’s minimum performance requirements for indoor air

quality and thermal comfort in schools. These performance requirements have been set to enable the

design and upgrade of schools to be in in line with the Ministry’s expectations on learning

environments. These spaces should support a variety of teaching and learning approaches, while also

providing adequate levels of comfort, and ensuring an environment conducive to good health and

wellbeing.

Designers will need to consider four key performance outcomes and associated control measures:

indoor air quality – Section 1.1

ventilation design – Section 1.2

indoor temperature range and control – Section 1.3

provisions for teacher and student monitoring and control of indoor air quality and temperature –

Section 1.4.

These minimum requirements ensure compliance with existing statutory obligations, and go beyond

the minimum standards required by the New Zealand Building Code (BC) to ensure appropriate

ventilation and temperature control are provided to support good education outcomes in our learning

spaces. These standards draw on a variety of relevant national and international best practice

standards and guides.

Local environmental factors will also have significant implications for all aspects of the building design.

Consideration of site-specific environmental factors is a key part of the design optimisation process,

and a key part of these requirements.

Designers should develop specific design solutions that ensure good and balanced performance

outcomes across all parameters.

1.1 Indoor air quality and minimum fresh air ventilation requirements

Indoor air quality is an important environmental measure that research suggests has a significant

impact on academic performance in schools. The Ministry wants to ensure adequate outdoor air is

provided to each learning space to ensure students and teachers can learn and work comfortably in

the space. The concentration of carbon dioxide (CO2) in the air is a good marker to check the general

indoor air quality. This is measured in parts per million (ppm).

The concentration of CO2 in outside air depends largely on the geographic location, air movement

effects (wind) and proximity to air pollutant sources (such as roads, heavy industry or geothermal

areas). Research suggests that normal urban atmospheric concentrations range from 450-600 ppm.

In enclosed spaces, normal respiration rates of occupants will naturally increase CO2 levels above

atmospheric levels. Figure 1.1 illustrates the relationship between indoor CO2 concentrations,

ventilation rates expressed both as air changes per hour (ACPH), as litres per second per person

(L/s/P), and various performance metrics (subjective occupant response, normalised student

performance and school absenteeism). The performance outcomes associated with CO2

concentrations and ventilation rates are based on findings from Barrett et al. (2015) and Chatzidiakou

et al. (2014).


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1.2 Performance requirements

the average concentration of CO2 should not exceed 1,500 ppm when measured at seated head

height (1200mm), during the continuous period between the start and finish of teaching on any

day. An average of 1200 ppm or lower is required

the maximum peak concentration of CO2 should not exceed 3,000 ppm during the teaching day

at any occupied time, the occupants should be able to purge air to lower the concentration of CO2

to 1,000 ppm within 10 minutes

a purge threshold of 800 ppm or lower is recommended

a CO2 monitor with direct reading display is to be provided in a central location in each learning

space. This is to assist the teaching staff and students to manage CO2 by opening windows etc.

Refer to Section 1.4 for further details

provide appropriate local ventilation devices for specialist technology spaces. Refer to Section 4

for further details

for new or upgraded learning spaces, the building materials and components should be specified

to fall below the maximum allowable VOC-content, or the maximum allowable VOC-emission rates

as described by the New Zealand Green Building Council (NZGBC) Education Technical Manual

provide entry/exit mats at principal entry/exit points to mitigate dust and dirt tracking from outside

to inside.


Figure 1.1 School indoor air quality, ventilation parameters and performance outcomes.Indoor air quality considerations.


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CO2 concentrations for buildings naturally fluctuate over the day depending on the occupant load,

activities being performed and time of year. The ability of occupants to open and close doors and

windows will also affect the internal air quality. This can be seen in the following two figures which

illustrate the typical pattern and significant variability of CO2 concentrations.

i

Figure 1.2 An example of measured CO2 concentrations (ppm) for a naturally ventilated flexible learning space in

Auckland over one week period during winter.

Figure 1.3 An example of measured CO2 concentrations (ppm) for a naturally ventilated flexible learning space in

Auckland during a winter’s day.

10 minute purge

threshold of 1000 ppm

Maximum daily

average 1500 ppm

Actual daily average

1220 ppm

Maximum daily limit

3000 ppm


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CO2 concentrations

In Figure 1.2, CO2 concentrations rise and fall over the course of a typical day and follow a similar

pattern over the week.

In Figure 1.3, CO2 concentrations rise from a base of 400 ppm (equivalent to external atmospheric

CO2 concentrations) to peak of ~2,200 ppm at around 11am. CO2 concentrations then drop over the

lunchtime period before rising again to a secondary peak of ~1000 ppm around 3pm. Being winter,

windows and doors are generally closed first thing in the morning to conserve heat. Over the course of

the day windows and doors are opened as occupants move between indoor and outdoor learning

environments, or in response to feelings of stuffiness as CO2 concentrations, temperature and

humidity increase.

By way of context, the NZ Workplace Exposure Standards specify an average CO2 concentration limit

of 5,000 ppm over the course of an eight hour day and a five day working week (the Time Weighted

Average limit – TLV-TWA). The specified short-term exposure limit is 30,000 ppm over any 15 minute

period (TLV-STEL).

CO2 and other respiration derived pollutants

CO2 is recognised as a useful proxy for respiration derived pollutants (including airborne pathogens

and anthropogenic odours1). Due to the range of sources and types of possible pollutants, it is difficult

to define an acceptable threshold for all indoor pollutants. In typical non-specialist learning

environments general pollutant levels may be reasonably characterised by the amount of CO2 in the

air. The CO2 concentration limits set out above are intended to serve as a limiting proxy for a range of

other airborne pollutants.

The available evidence indicates that even the highest CO2 concentrations likely to be encountered in

learning spaces in schools would not in themselves constitute a risk to health, but rather a temporary

impediment to cognitive performance, particularly in relation to speed.

Particulate matter

Particulate matter (PM) is an air-suspended mixture of solid and liquid particles from both human and

natural sources. PM is normally classified by size (PM10 includes particles of


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Volatile Organic Compounds

A wide range of VOCs and other potentially harmful substances may be emitted by building materials,

furnishings and appliances. These are of particular concern in new or recently refurbished and

refurnished buildings, as VOC emissions are typically highest from new products and diminish over

time. Concentrations of these pollutants may be controlled through the specification of low VOC-

content products, and through the specification of adequate ventilation strategies and temperature

ranges1.

There is evidence to suggest that maintaining classroom temperatures below 26°C (and preferably

below 22°C) may also reduce VOC concentrations2. CO2 concentrations may be a poor proxy for

these types of pollutants, particularly in the context of new or recently refurbished and refurnished

buildings. However, the broad range of specific compounds, variable toxicities, and wide variety of

VOC sources make this class of pollutants difficult to set standards for effectively and completely.

Pollutants in specialist learning spaces

A wide range of other pollutants may be encountered in specialist learning spaces such as

laboratories, workshops and art studios. These are discussed in Section 4.

1.3 Ventilation design strategies

Ventilation may be provided through either natural or mechanical means. The strategy employed will

depend on the form of the school building, its size, occupancy density, acoustics and other site

specific requirements. Wherever practical, natural (passive) or semi-natural (passive) ventilation is

preferred by the Ministry, provided minimum requirements in terms of pollutant control, and

temperature level stability and control, are met.

Natural ventilation entails the provision of windows and other vents that may be manually opened and

closed. Natural ventilation is usually associated with smaller, spatially simple enclosures, but can be

an effective strategy in larger spaces with careful modelling and specific design. Natural ventilation

relies on internal-external air pressure differentials, or on vertical thermal differentials within building

spaces (the ‘stack effect’), to drive air movement.

Mixed natural/mechanical and wholly mechanical ventilation is suited to larger, spatially complex

enclosures with moderate to high occupancy levels. Mechancial ventilation may also be appropriate

for internal rooms in deep plan buildings, or where acoustic requirements preclude the use of natural

ventilation.

Different design principles govern each strategy; they are addressed separately below.

Natural ventilation (passive)

Minimum outdoor ventilation rates nominally equivalent to four air changes per hour, providing

approximately eight litres per second per person, will be considerably exceeded by opening windows

in warmer weather. It is expected that the summer range of CO2 levels will vary from approximately

400 ppm to 1,000 ppm over the course of a day. Maintaining good indoor air quality in naturally

ventilated buildings during cold weather is more difficult and relies, to a certain extent, on staff

intervention to open windows, as described in Section 1.4.

1 Chatzidiakou (2014), p. 175

2 Ibid., pp. 168, 175; Kagi et al., (2009)


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In warm climate zones, the provision of trickle vents and a range of window opening arrangements

with a CO2 monitor, can meet the requirements of Section 1.1.

Mixed natural/mechanical ventilation

Natural ventilation arrangements are to be supplemented by additional powered or non-powered

supply/exhaust systems with variable flow capability linked to CO2 automatic control where buildings

have:

deeper plan

single sided ventilation that cannot be naturally ventilated adequately

complex building shapes with airflow deadspots.

Also consider spaces such as breakout areas where doors may be closed during a classroom session.

In cold climate zones where natural outdoor air ventilation may result in cold draughts and discomfort,

mechanical heat recovery or mixed-mode ventilation is to be considered.

Mechanically ventilated

Where natural outdoor air ventilation is precluded, a filtered mechanical outdoor air ventilation system

is to provide the minimum flow rates as per NZS 4303:1990 Ventilation for acceptable indoor air

quality or AS 1668.2:2012 Mechanical ventilation in buildings, and as per the particular Ministry

requirements given in Section 4.

For example, for schools in cold climate zones where natural ventilation would result in cold draughts,

for internal rooms, for acoustic reasons, for external pollutant reasons, or because the spaces are of a

specialist nature with specific ventilation requirements as described in Section 4.

1.4 Indoor temperature levels, stability and control

Overheating, rather than underheating, is the key concern in new schools due to better building

insulation and airtightness, particularly in schools without active cooling. Evidence indicates that

children attending schools in temperate climates may be more sensitive to higher temperatures than

adults and that they generally prefer conditions to be a few degrees cooler due to their higher

metabolic rate and activity levels over the course of a school day.

Figure 1.4 below indicates that if higher temperatures over summer are present in the learning space,

they may have a reasonably significant effect on student performance, particularly in terms of

cognitive speed. However, in practice these elevated temperatures may only persist for a few hours a

day during warmer weather.

Indoor temperature should remain within a comfortable range throughout the school day. However,

what feels comfortable will vary according to the time of day, relative humidity, radiant temperatures,

occupant activity levels, air movement, and individual preference. There are a number of artificial

comfort or operative temperature equivalents that attempt to consider all these factors.

The subjective comfort levels reported by occupants in free running naturally ventilated buildings

without recourse to air conditioning have also been found to be related to the prevailing outdoor

temperature, and in particular to the running average in the preceding few days. In simple terms,

higher internal temperatures become more tolerable to occupants during sustained periods of warm

weather.


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This adaptive concept of comfort relies on the occupants being able to adapt their space and clothing,

for example:

opening windows for increased air movement

operating blinds to block out sun or providing external sun shading

switching on ceiling fans

wearing lighter clothing in summer

having regular access to drinking water.

Models have been developed by both ASHRAE (ANSI/ASHRAE Standard 55) and CIBSE (CIBSE

TM52) that take into account all the above factors in a holistic way. Their application is fairly complex

to evaluate, although available computer software can automate this task. The CIBSE version TM52

also relies on the development of Design Summer Year (DSY) files rather than the Typical

Meteorological Year (TMY) files commonly available in New Zealand.

For this reason, a modified version of the more established performance standards given in the CIBSE

Guide Book A, and in the UK Building Bulletin 101 – Ventilation of School Buildings has been used as

the basis of the Ministry’s requirements. These standards have been modified by the use of modelling

in different New Zealand locations to determine locally appropriate hours of exceedance values. They

use fixed air temperature rather than variable adaptive temperature as a metric.

If DSY files are developed for New Zealand locations, then the use of CIBSE TM52 as an alternative

overheating standard at the design stage is considered acceptable.

Minimum temperature requirements

all learning spaces (except gymnasiums) are to be provided with a heating system sufficient to

maintain a minimum temperature of 18˚C during normal periods of occupation, measured at a

height of 1m above floor level

administration, resource work and meeting spaces, and staffrooms are to be provided with a

heating system sufficient to maintain a minimum temperature of 20°C during normal periods of

occupation, measured at 1.5m above floor level

spaces such as corridors and multipurpose halls and gymnasiums are to be provided with a

heating system sufficient to maintain a minimum temperature of 16°C during normal periods of

occupation, measured at a height of 1.0 m above floor level

provision for heating Universal School Bathrooms (formerly High Dependency Units) is required,

so that these rooms can be heated to 22°C

the use of radiant panel type heaters is recommended for Universal School Bathrooms

toilets and change rooms are not required to be heated.

Heating system recommendations

Heating systems are to be appropriate to the climate zone and the longterm availability of fuel/energy

sources. A lifecycle costing/options report is required as described in Section 5.7.

Systems that could be considered include:

central boiler systems in conjunction with low surface temperature radiators, underfloor heating or

warm air fan coils. Consider alternative and available fuel sources, eg natural gas and wood

chip/pellet. New coal-fired, fuel, oil, electric, and LPG boiler installations are to be avoided

air or ground source hot water heat pump along with underfloor heating or warm air fan coils

electric radiant heating


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reverse cycle, split air conditioning heat pumps

reverse cycle multi split, variant refrigerant flow (VRF) air conditioning systems

packaged ducted air conditioning systems.

Each principal activity space is to be capable of individual zone temperature and time control. It should

be possible to override the time control to provide additional heating in each space by the provision of

afterhour switches to allow for pre and after school use of individual spaces.

Maximum internal temperature requirements

Schools are to be designed to ensure overheating does not occur.

Overheating can cause thermal stress to occupants and creates uncomfortable indoor environments.

Overheating is most likely to occur during summer months for the occupied period of 9am to 3:30pm,

Monday to Friday. For design modelling purposes, summertime is between the dates 10 October to

20 December, and 1 February to 15 April (school terms 4 and 1 respectively).

To show that the proposed school building will not suffer overheating, learning spaces, libraries,

administrative offices, staffrooms and multipurpose spaces are to be designed to comply with at least

two of the following three criteria:

(1) there should be no more than the number of hours given in Table 1.1 when the air temperature

in the classroom rises above 25°C and 28°C

(2) the average internal to external temperature difference should not exceed 5°C (ie the internal air

temperature should be no more than 5°C above the external air temperature on average over a

day during school hours)

(3) the internal air temperature when the space is occupied should not exceed 32°C.

Criteria notes

Gymnasiums and ancillary spaces are excluded from these criteria. However, good thermal design

principles should still be applied.

Condition (1) describes the amount of time that overheating above a desirable maximum

temperature of 25°C and to an elevated temperature of 28°C. The latter temperature indicates the

upper limit of internal temperature that is considered both hot and uncomfortable.

Condition (2) ensures that the change in temperature staff and students experience moving from

outside to inside remains within tolerable limits. The lower the value the more desirable. 5°C

represents the upper threshold.

Condition (3) describes the maximum temperature of 32°C above which it is highly undesirable to

exceed.

The designer is to demonstrate within a project’s preliminary or developed design report that the

maximum summertime temperature requirements described above will be met for learning spaces and

multipurpose spaces only.

For simple building forms, provision of a design statement and any supporting calculations will be

sufficient (types 1A, 2A and 1B, as described in Figure 2.8).

For more complex building forms, the design statement is to be supported by a thermal modelling

report (types 2B and 2C, as described in Figure 2.8).


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Cooling requirements

In naturally ventilated spaces, high summertime temperatures can be mitigated by low-noise variable-

speed ceiling sweep fans.

The cooling effect of these local fans can be equivalent to reducing the perceived comfort temperature

by around 2°C.

Ventilation openings should have a combined area of between 7.5 to 10% of the floor area.

The representative window area being the total face area of the openable vents and assuming an

aerodynamic area coefficient of approximately 50%. Modelling can provide a more accurate

assessment of the aerodynamic areas of differing window types.

If vents are more constricted than this then the percentage area of openable vents to floor area should

be increased on a pro-rata basis. The ventilation area should be well distributed, ideally with high and

low level openings, and wherever possible are to be configured to avoid stagnant air pockets.

Reliance on opening doors as the predominant means of natural ventilation should be minimised.

Preference is given to more operable and controllable vents and windows, which should provide a

range of ventilation openings suitable for different times of the year.

Active cooling system recommendations

Where it can be demonstrated by modelling that the summertime temperature criteria given in (1)

above cannot be reasonably achieved by natural ventilation and good passive design, then

mechanical ventilation may be considered as more appropriate for summertime temperature control.

This is more likely to be the case for new school buildings in locations with warmer summer

temperatures (Northland, Auckland, Hawkes Bay, Nelson/Blenheim and Christchurch).

Some specialist spaces should always be provided with active cooling as described in Section 4.

Other administrative spaces that require high levels of acoustic privacy may be provided with cooling

at the discretion of the Ministry and the school.

Energy efficiency for both the energy consumed in circulating air, and the energy consumed in

heating/cooling should be of concern to designers. Careful analysis is required in order to provide

justification on a school-by-school basis.

Appropriate use of a HVAC system may also include:

sites that are affected by high levels of road or air traffic noise, or that generate significant noise

themselves (eg music rooms or workshops)

sites that are exposed to high levels of pollen or other outside air contaminants may also require

mechanical ventilation and filtration

school building forms with excessively deep spaces where natural ventilation may not be feasible

spaces of a specialist nature, eg performing arts centres

buildings where the amount of air required for summertime temperature control are large, and

analysis deems it inefficient and costly to operate heating/cooling separately.

Where an HVAC system is required and agreed by the Ministry, then the system is to be sized and will

operate with set points 2°C below the NIWA 1% summer dry bulb design temperature (ie if the NIWA

1% summer design temperature is 27°C, the system is to be designed and operated to maintain

25°C).


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Allowances are also to be made for adjusting the current NIWA 1% design criterion for increased

incidence of extreme conditions as predicted by Ministry for the Environment’s climate change

projections. HVAC systems to be considered include:

reverse cycle split air conditioning heatpump in conjunction with minimum CO2 controlled outdoor

ventilation system, with or without heat recovery depending on climate zone

reverse cycle multi split or hybrid VRF air conditioning systems in conjunction with minimum CO2

controlled outdoor ventilation system, with or without heat recovery depending on climate zone

all air packaged air conditioners with ducted supply and return/spill air complete with economiser

cycles and CO2 controlled minimum outside air control.

The choice of HVAC system may be subject to a lifecycle cost benefit analysis, as described in

Section 5.7.


Figure 1.4 School Indoor Temperature Parameters. For allowable hours above 25˚C (Threshold 1) and 28˚C (Threshold 2) refer to Table 1.1


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Table 1.1 Allowable hours above 25°C and 28°C for New Zealand schools in specified locations during the

occupied period of 9am to 3:30pm, Monday to Friday from 10 October to 20 December, and 1 February

to 15 April.

Climate zone Sub zone towns/cities*

No. of hours above

25ºC 28ºC

North Island 1 – Warm

Northern North Island Kaitaia, Whangarei, Auckland 250 50

North Island 2A – Cool

Central North Island Hamilton, Rotorua 150 10

South West North Island New Plymouth, Whanganui, Palmerston North, Wellington

150 10

North Island 2B – Warm

Eastern North Island Gisborne, Napier, Hastings, Masterton 250 60

North Island 3A – Cool

Central North Island Taupo 150 10

South Island 3B – Warm

Northern South Island Nelson, Blenheim 150 20

South Island 3C – Cold

Western South Island Westport, Hokitika, Greymouth 50 10

Eastern South Island Kaikoura, Christchurch, Timaru 150 40

Inland South Island Wanaka, Queenstown, Alexandra 50 10

Southern South Island Dunedin, Invercargill 20 10

*For demarcation of climate zones and sub-zones see Figure 1.5.


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Figure 1.5 New Zealand climate zones and sub-zones.


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Climate change effects

The Ministry for the Environment’s Climate Change Projections for New Zealand (2016) concludes

that climate change effects will result in higher temperatures, with greater increases in the North Island

than in the South, with the greatest warming in the North East. The amount of warming in New

Zealand is likely to be lower than the global average. Warming will be greatest in the summer season,

and least in winter and spring.

Temperature extremes are anticipated to change significantly by the end of the century, with maximum

temperatures of 25˚C or more predicted to double or quadruple in frequency. The Ministry’s

overheating criteria requirements are therefore likely to change over time, with greater reliance on

active cooling in warmer regions. This response should be viewed in conjunction with the anticipated

lifecycle of heating/cooling systems, typically 15 to 25 years, and also with the need to minimise

greenhouse gas emissions in the short to medium term.

1.5 Provisions for teacher monitoring and control of environmental conditions

In naturally ventilated and passively controlled learning spaces, teaching staff and students have a key

role in maintaining the CO2, ventilation and temperature requirements given in Sections 1.1, 1.2 and

1.3. However, teachers are busy performing their pedagogic role and are sometimes uncertain of their

role in maintaining conditions in the classroom. Research suggests that teachers frequently

underutilise windows, resulting in inadequate ventilation5. It is also recognised that maintaining a

healthy and comfortable internal environment is a good life skill for students to acquire.

Operation of windows and doors in learning spaces needs to be as simple and intuitive as possible,

and should be supported by good information regarding when to open doors and windows, and by

how much.

Allocation of the responsibility for opening windows becomes more complex in flexible learning spaces

which are shared by a larger number of students and teaching staff. Their interconnecting spaces also

raise the potential for disrupting cross-ventilation. Consideration should therefore be given to the

extent to which students should be able to control ventilation rates.

Ministry requirements

Provide CO2 and internal/external temperature display in a central location within each learning space,

with instant visible feedback to local users. This is to be provided with either:

a) a simple laminated or framed user guide adjacent to the display. A simplified example is given

in Figure 1.8. Note that this must be altered as appropriate to suit the specific design of the

teaching spaces; or

b) an electronic display device to be used with inputs from the CO2 and internal/external

temperature monitors, with a graphic display of actions required by users.

Educate and require the teaching staff to appoint student monitors in each learning space to take joint

responsibility for looking at the temperature and CO2 levels at the start and finish of each school

period, setting the windows/vents, and operating the ceiling fans accordingly.

5 Gully (2015), p. 29; Liaw (2015), Table 13, pp. 37-38


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Figure 1.6 Combined inside/outside temperature, CO2 (ppm) and relative humidity display device.


Figure 1.7 Interactive control display.


Figure 1.8 Teacher window position and ceiling fan matrix to be reviewed at start and finish of each period/lesson. Actual settings will depend on ambient wind and noise

conditions


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2 New Buildings

2.1 Introduction

This section covers design considerations relevant to new learning environments. It explains how the

Ministry’s requirements and recommendations set out in Section 1 apply to new buildings, and

includes a range of potential strategies and design solutions.

Heating, ventilation and cooling design must meet the Ministry’s minimum requirements as specified in

Section 1 as well as any relevant requirements contained in other DQLS guidelines. Designers will

need to apply an integrated approach to the design of schools and the learning spaces within them.

Acoustics, temperature control, ventilation, lighting and energy use are all interrelated, and a change

to one environmental factor may impact on others. This guideline should be read in conjunction with

other guidelines in the DQLS suite.

Heating, ventilation and cooling design must also meet the overarching requirements set out in the

Ministry’s Designing Schools in New Zealand - Requirements and Guidelines along with Ministry

requirements of efficiency, durability and cost effectiveness.

The selection of heating, ventilation and cooling strategies, and of specific plant and building

components, should be informed by a careful comparative analysis of the lifecycle costs and benefits

of the competing options. Further requirements with regard to lifecycle costs and the comparative

benefits for heating, ventilation and cooling systems are given in Section 5.7.

2.2 Integrated passive design approach

With traditional design processes, when just 10% of a project’s cost has been expended, 70 to 80% of

the lifetime costs and consequences of the building will have been effectively locked in. An integrated

whole building design process develops an overall building design by workshopping a range of design

options and solutions that offer positive outcomes across all design disciplines: architectural,

structural, services, acoustics, fire etc.

Integrated design

Integrated design brings together the various specialist disciplines that contribute to the overall design

process of a building or project. For new school projects, collaboration between specialist design

disciplines should ideally occur early in the design process, at the master planning and preliminary

design stages. Integrated design seeks to exploit available synergies between different design

disciplines and to avoid conflicts between the various design strategies developed by each discipline.

Integrated design plays a key role in maximising indoor environmental quality and energy efficiency

across the range of relevant building services.


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Figure 2.1 Integrated design process.

Further guidance can be found in the Ministry for Environment’s Integrated Whole Building Design

Guidelines.

Passive design

Passive design seeks to adopt design strategies that take advantage of local environmental and

climatic conditions. A principal aim of passive design is often to minimise the building’s energy use.

Passive design strategies may be employed across the range of specialist design disciplines including

lighting, acoustics, heating/cooling and ventilation. Passive design strategies frequently involve more

than one specialist design discipline – a passive temperature control strategy, for example, may have

implications for lighting, ventilation and structural design. Good passive design usually requires an

integrated design process, as described above, that brings together all of the specialist disciplines that

contribute to the overall design of a building or project.

In order to adapt to – and exploit – the local site characteristics, it is important that a thorough

understanding be gained of the site’s environmental and climatic conditions. A detailed study of the

site’s environmental and climatic features, including a site specific load chart similar to that presented

in Figure 2.2, should form a key input into the master plan and preliminary design stages of projects.

Important elements of passive design include building location, form and orientation, internal layout,

window design, thermal resistance of the building envelope, distribution of thermal mass within the

building, external shading of the building and passive ventilation design. Each of these elements

should complement the others in order to achieve comfortable temperatures, good indoor air quality,

good acoustics, good natural light and a high degree of energy efficiency.

Building design features can either support or present challenges to the achievement of passive

design goals. Building design features that particularly affect passive temperature control and natural

ventilation are highlighted in Table 2.1.

http://www.mfe.govt.nz/sites/default/files/integrated-building-guidelines.pdfhttp://www.mfe.govt.nz/sites/default/files/integrated-building-guidelines.pdf


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Table 2.1 Key design features affecting the success of passive temperature control and natural ventilation.

Success factors Problem issues

Shallow plan building design Deep plan building design

Two-sided façade and uninterrupted airflow Single-sided and cellular narrow plan

High ceilings Low ceilings

Thermally heavyweight construction Thermally lightweight construction

Well designed and distributed windows with a range of opening options, suitable for use in changing external conditions

Poorly designed and distributed windows

High efficiency LED lighting and equipment Low efficiency lighting and equipment

Low external noise levels; controlled indoor ambient noise levels

High external noise levels; uncontrolled indoor ambient levels

Solar gain and inside/outside heat transfer are significant sources of incidental heat in most learning

environments. In general terms, solar gain and ambient heat sources add an average of 25 watts per

square metre (W/m2) on a relatively sunny day with reasonable solar control.

There are other significant sources of heat that should be considered during the passive thermal

design process. Students and teachers may generate in the vicinity of 60 to 80 watts of heat energy

respectively when seated. This is equivalent to 30 W/m2 of peak heat gain released into the learning

environment.

The increasing use of personal electronic devices, such as laptpops and tablets, also results in a large

number of small heating sources distributed throughout the learning space. Although the power

demand of these devices is falling, their prevalence is only likely to increase. Other electronic

appliances such as printers, projectors and TV screens can also generate significant amounts of heat.

Specification of low-energy appliances may help to reduce overall energy use, while also lowering the

extent of overheating or the need for active cooling during summer months.

The potential for lighting efficiency continues to improve, particularly with the use of T5 fluorescent and

LED lamps, and through occupancy controls. Perimeter lighting can also be circuited to allow it to be

switched off when adequate daylight is available. Lighting can release around 6 W/m2 of heat energy

into the learning environment.

Averaged over the whole day, a learning space might expect an average heat load of 40 to 60 W/m2,

which is released as heat into the learning environment.

Load charts are a good way to look at the effects of these heat gains. They are a simplified graphical

plot of average heat gain against outside air temperature. Typical load charts for Auckland and

Dunedin learning spaces are presented in Figure 2.2 and Figure 2.3, respectively.

The maximum heat loss/minimum heat gain line is for an unoccupied space and represents the

building fabric and infiltration loads only. It crosses the outside temperature axis at the winter design

temperature balance point of 18°C, and at the winter design temperature the load represents the

design winter heat loss. The minimum heat loss/maximum heat gain line includes all the effects of

occupants, lights, equipment, solar, fabric and infiltration for an occupied space. When these loads are

taken into account it can be seen from the chart that the balance point shifts downwards from 18°C to

9°C. This means that whenever the outside air temperature is above 9°C and the learning space is

occupied, it does not require any heating, and that overheating may start to occur at outside

temperatures of around 18°C.


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What the load chart indicates is that occupied learning spaces can heat up when subject to solar gain

and internal heat gains. Although heating may be required early in the morning during spring and

autumn to achieve the minimum required temperatures, overheating may quickly become an issue as

the outside temperature rises (especially if inclement weather deters the opening of windows). A

building may therefore need to shift into a passive cooling mode, particularly in warmer climate zones.

In well insulated schools, overheating, rather than underheating, is therefore the critical design driver

for most of the school year in the majority of New Zealand school locations. Designers should consider

ways to moderate any detrimental effects and ensure that excess heat can be vented when required.

Passive cooling of larger spaces to mitigate these heat gains is primarily provided through wind driven

cross-flow ventilation via opening windows.

Thermally-driven passive (or ‘stack’) ventilation may also be provided, particularly if the space has

sufficient height to support a robust stack effect. This can be particularly helpful on hot, still days.

Other passive cooling strategies may include:

minimising excess solar gain (through window design, placement and shading)

insulation to prevent heat gain

thermal mass to absorb excess heat (with stored heat vented at night, or utilised in the early

morning)

use of eaves or external shading devices, such as sun screens or deciduous trees, to control solar

gain

internal blinds to mitigate the effects of direct sunlight on teaching staff and students close to

windows.


Figure 2.2 An example thermal load chart for Auckland, showing load variation over the course of a year. As average internal heat gains from various sources increase (solar,

occupants, lighting, etc.), so must the number of passive design features as indicated in the margin to the right of the chart.


Figure 2.3 An example thermal load chart for Dunedin, showing load variation over the course of a year. As average internal heat gains from various sources (solar, occupants,

lighting, etc.) increase, so must the number of passive design features as indicated in the margin to the right of the chart.


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2.3 Building form

The form of the building can have a significant effect on the internal environment and on the utilitsation

of passive energy sources such as natural ventilation and natural light. Generally, narrow building

forms allow greater utilization of natural ventilation and natural light. Single storey buildings also allow

the roof design to be utilized more fully in deeper plan spaces. However, the building should not be so

narrow that the learning environment is compromised. As a general guideline, 12-14m spans provide

good levels of internal flexibility whilst still enabling good neutral levels of ventilation and daylight.

The environment in the lower storey of two storey buildings is generally easier to control than the

upper storey.

As building forms become deeper, more complex and more subdivided internally, reliance on passive

approaches becomes increasingly challenging.

The pros and cons of differing building forms with particular regard to ventilation design are discussed

further in Figure 2.8. Similar justifications can be made for availability of natural light.

For larger learning spaces, increased building heights and volumes can help to stratify heat and

encourage a robust stack effect and to assist in cross ventilation.

The ratio of height to depth is an important factor in natural ventilation design.

2.4 Orientation

Where feasible thorough site planning, large elevations of east and west facing glass should be

avoided in order to control and prevent associated glare and solar gain issues. Windows orientated to

the north and south are easier to shade.

An ideal orientation generally lies between +/- 30° North.

Figure 2.4 Building orientation shading to help manage solar gain.

This orientation minimises shading requirements and maximises the efficiency of any shading devices

used.

Windows should also be oriented away from busy roads/streets wherever possible to minimise the

effects of noise and pollutants on the internal environment.


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2.5 Window to wall ratio, glazing and shading

Although light is a key design parameter, window size alone is not significantly correlated with learning

outcomes. Only when orientation, risk of glare and overheating are taken into consideration, can

students benefit from optimum glazing size. The effects of shortwave solar radiation from sunshine

falling on a person can elevate the perceived air temperature by 4 to 5°C.

The average window area should be around 30 to 50% of the wall area. Window areas should be

concentrated across the southern, northern and eastern elevations (subject to appropriate shading).

Large windows to the west should be minimised.

A wide selection of glazing is available, variously designed to maximise acoustic insulation, minimise

transmitted solar gain, maximise thermal insulation, or some combination thereof. Two useful rating

values for glazing are the solar heat gain coefficient (SHGC) and thermal resistivity (R-value).

Shading coefficients range from above 0.82 for uncoated clear single pane glass, to less than 0.60 for

double glazing with a low emissivity pane and argon gas fill.

There is a preference in schools for the use of clear (or at most, lightly tinted) glass with a light

transmittance >70% (in conjunction with shading where necessary). Reflective or heavily tinted glass

should be avoided.

Additional shading can be provided in a variety of architectural ways, such as by overhangs, louvres,

brise soleil, fins and covered walkways.

Shading by itself is seldom fully effective at all times of the day and year, therefore internal blinds

should be provided where required. The interaction between internal blinds and ventilation openings

needs to be carefully considered. Window design should allow the deployment of blinds whilst not

obstructing all ventilation openings.

Glazing with a high R-value is appropriate where a well insulated thermal building envelope is required

due to location. This will minimise heat loss through the window when external temperatures are

below internal temperatures. In summer, high R-value glazing may contribute to overheating, its use in

warmer climates should be carefully considered.

The achievement of natural lighting goals will have implications for the thermal design strategy.

Passive lighting and passive thermal control are closely allied, the two need to be carefully considered

and jointly optimised.

Daylighting design analysis should be undertaken to ensure maximum benefit is gained from the

available resources. Due to the clear skies and variation in sunshine hours experienced in

New Zealand, natural lighting analysis should adopt a climate based modelling approach, rather than

using a minimum daylight factor. The daylight factor approach can be unduly conservative and may

lead to excessive glazing with subsequent overheating issues.

Refer to the DQLS – Lighting guidline for further information on natural lighting design.


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Figure 2.5 Combination of sunscreens and overhangs provide a good level of solar shading and protection.

2.6 Thermal insulation

Effective thermal insulation requires good thermal design, adequate materials (as expressed by the

material’s R-value) and high quality installation.

The full annual range of climatic conditions should be considered during the design process.

Depending on local conditions and on the climate zone it may be as important that a building shed

heat in summer, as it retains heat in winter. The general specification of high R-value components

may not be the most appropriate strategy. Selective distribution of insulation, thermal mass and

natural ventilation may assist in moderating internal microclimates, while delivering an overall energy

efficient building.

Robust thermal modelling of the building is recommended for significant projects.

Table 2.2 details the Ministry’s requirements for thermal insulation. The Ministry’s recommended

minimum levels of insulation seek to address the tradeoff between winter heat retention and summer

heat loss.

Specification of adequate insulation material is not in itself sufficient to ensure good thermal

performance. Proper installation of insulating material and insulated building elements is essential,

otherwise small gaps, thermal bridges and recessed lights can allow significant heat loss. Where

thermally-conductive building components such as structural beams penetrate the thermal envelope,

these components should be insulated.


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Table 2.2 Ministry requirements for thermal resistance of building components for new buildings and major

upgrades.

Climate zone Sub zone Town/City Building component Ministry insulation requirements*

North Island

1 - Warm

Northern

North Island

Kaitaia

Whangarei

Auckland

Roof R 3.4

Wall R 2.2

Floor R 1.3

Windows R 0.15 (single glazing)

North Island

2A - Cool

Central

North Island

Hamilton

Rotorua

Roof R 3.4

Wall R 2.2

Floor R 1.3

Windows R 0.26 (IGU)

South West

North Island

New Plymouth

Whanganui

Palmerston North

Wellington

Roof R 3.4

Wall R 2.2

Floor R 1.3


North Island

2B - Warm

Eastern

North Island

Gisborne

Napier

Masterton

Roof R 3.4

Wall R 2.2

Floor R 1.3

Windows R 0.15 (single)

North Island

3A - Cool

Central

North Island Taupo

Roof R 3.6

Wall R 2.6

Floor R 1.9


South Island

3B - Warm

Northern

South Island

Nelson

Blenheim

Roof R 3.6

Wall R 2.6

Floor R 1.9


South Island

3C - Cold

Western

South Island

Westport

Hokitika

Greymouth

Roof R 3.6

Wall R 2.6

Floor R 1.9


Eastern

South Island

Kaikoura

Christchurch

Timaru

Roof R 3.6

Wall R 2.6

Floor R 1.9


Inland

South Island

Wanaka

Queenstown Alexandra

Roof R 3.6

Wall R 2.6

Floor R 1.9


Southern

South Island Dunedin Invercargill

Roof R 3.6

Wall R 2.6

Floor R 1.9



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*Note: this column is used for situations where a new building is not being computer modelled.

Reference to Insulated Glazing Units (IGU) covers double and triple glazing. These minimum Ministry

requirements generally meet or exceed the Building Code requirements as set out in NZS 4218 (2009)

and NZS 4243 (2007). Higher levels of thermal insulation and better glazing should be considered in

remote school locations where the electricity tariff is high.

Figure 2.6 Installation of thermal insulation during construction of a flexible learning space upgrades.

Interstitial condensation within the building construction should be avoided through the use of:

suitable design to prevent condensation, refer to the latest research on aggravated thermal

bridging

effective thermal breaks between linings, framing members and exterior envelope

provision of ventilated voids within the construction, especially for roof spaces with raking ceilings

the use of vapour control on the warm side of the insulation where required, and

specification of appropriate space ventilation and heating.


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Thermal bridging and condensation control strategies are to be reviewed as part of the building

weathertightness peer review process.

Refer also to the Ministry’s Weathertightness and Durability Requirements and MBIE for more

information on the management of aggravated thermal bridging.

2.7 Thermal mass

Deployment of thermal mass may be useful in local climates characterised by a significant

temperature range during a day.

Thermal mass can assist in summer by absorbing ambient heat during peak times, controlling

overheating, and then releasing the stored heat when ambient temperatures drop. Heat may either be

released when required during the school day, or vented overnight if secure ventilation outlets are

provided.

Thermal mass can also help to absorb solar energy during winter, which can then be distributed

throughout the building during the school day.

Thermal mass elements may include areas of exposed concrete structure, masonry or precast

concrete walls, thermomass walls, or exposed concrete floors or floor soffits. Materials with high

specific heat capacity and high density are generally suitable for use as thermal mass elements.

Thermal mass elements need to be compatible with the acoustic requirements of the space. The

characteristics which make materials suitable for use as thermal mass elements (high specific heat

capacity and high density), may also affect the acoustic performance of the space – in particular the

acoustic reverberation time.

Consideration needs to be given to buildings using lightweight construction to manage potential

overheating from low thermal mass.

2.8 Pollutant control

The Ministry’s requirements for the control of atmospheric pollutants in learning spaces are provided in

Section 1.1.

Building components and materials must be specified to fall below the maximum allowable VOC

content, or the maximum allowable VOC emission rates, as prescribed by a NZGBC recognised eco-

label or indoor air quality scheme. Refer to Section 5.2 for further information.

New buildings must be designed, built and operated such that Ministry pollution control requirements

are met.

The principal design strategy for meeting the CO2 requirements will involve provision of adequate

ventilation. Design opportunities and challenges arise from:

the variable occupancy and activity levels expected in a flexible learning space

the overarching design imperative for flexible, more open, modular spatial layouts

the requirements that the design be energy efficient, durable and cost effective.

The various design principles and minimum requirements create a number of potentially conflicting

imperatives. The requirement for flexibility will tend to encourage higher levels of ventilation, with

implications for efficiency, cost effectiveness and sustainability. High ventilation rates may potentially

increase heating costs during cold weather and cooling costs during hot weather.


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The requirement that learning spaces be connected, multifunctional and more open plan can be both a

benefit and a challenge for the effective provision of passive ventilation, lighting and heating. Passive

ventilation is easier to achieve in smaller, enclosed spaces than in large, open plan buildings. Variable

occupancy and activity in a deeper plan and more complex space may necessitate the specification of

assisted natural ventilation or full mechanical ventilation. There may be implications for operating and

capital costs, particularly if natural cross-ventilation cannot be achieved.

In addition to CO2 and VOC contaminants, a range of other pollution sources need to be considered in

the general design of new school buildings. These include:

Cleaning and

maintenance materials:

These may be a source of volatile contaminants. Their storage and

use should be segregated in ventilated spaces away from learning

areas. Environmentally-friendly cleaning products should be used.

External particulates: Dust and other particulates may accumulate inside, where they settle

in fabrics and on surfaces and be periodically circulated back into the

internal air. Appropriate design of external spaces and building

access points may reduce walked-in dirt. Deployment of adequate

entry/exit mats may capture dirt at the entrance. Unpaved play areas

have been found to increase mineral contributions. Weekday road

traffic pollutants can also have an effect, particularly where windows

are orientated directly to the surrounding streets, rather than to the

interior of the block or to a playground.

Internal particulates: Nearly half the PM2.5 concentrations of particulates are generated

internally due to continuous re-suspension of soil particles (13%) and

particulates from a variety of other sources (34% comprises skin

flakes, clothing fibres, possible condensation of VOCs and calcium-

rich particles from chalk and building deterioration). Good quality

cleaning of schools is therefore very important. A good cleaning

regime using well maintained HEPA filtered vacuum cleaners and

environmentally friendly cleaning materials can reduce internal

particulate levels.

Mould: Persistent moisture can encourage growth of mould, which emit

spores and impair environmental quality. High standards of thermal

insulation, heating and ventilation should minimise the conditions for

mould growth

Pollen: Landscaping, planting and design of external spaces should minimise

local particulate sources; vegetation types that produce high levels of

pollen or other irritants should be avoided.

Rubbish: Particulates and odours emanating from rubbish. Bins and refuse

management systems should be located away from learning spaces

and air vents.

Spills, food scraps and

cooking odours:

From student activities and lunchtime meal preparation. Segregation

of food preparation and consumption areas may assist in containing

odours and particulates.


SE

CT

IO

N 2

Top-dressing and

pesticide sprays:

These are a particular concern in rural settings.

Vermin and animal

pests:

Nesting and roosting locations can be a source of particulate,

microbial and odorous pollutants. General building design should

avoid creating attractive roosting or nesting spa

DESIGNING QUALITY LEARNING SPACES Indoor Air Quality and ...€¦ · Designing Quality Learning...

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