Urban Spaces Thermal Conditioning a Comparative Study of Public Outdoor Spaces Passive Thermal...

8/9/2019 Urban Spaces Thermal Conditioning a Comparative Study of Public Outdoor Spaces Passive Thermal Conditioning

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Name: Ismail M Qaznili

Student ID: 4089241

Course: Sustainable Urban Design (K14SUD)

School: School of the Built Environment

Subject: MArch in Urban Design

Number of Words: (1900)

Urban Spaces Thermal Conditioning: A Comparative Study of Public

Outdoor Spaces Passive Thermal Conditioning.

May 2009


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Table of Contents

Introduction............................................................................................................ 1Outdoor Thermal Conditioning .......................................................................... 2The Concept .......................................................................................................... 2The Human Thermal Comfort............................................................................. 3The Methodology.................................................................................................. 4

Thermal Conditioning Case Study.................................................................... 5Matsudo Station Square ................................................................................... 6Matsudo Central Park ....................................................................................... 6Empirical Research Method............................................................................. 7The Results .......................................................................................................... 9

Conclusion .............................................................................................................. 12


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Table of Figures

Figure 1 Study Areas Location Map 8

Figure 2 - 3 Matsudo Square Platform and Street 9

Figure 4 5 Matsudo Park Walkway and Lawn 9

Figure 6 - 7 Right: Matsudo Square, Left: Matsudo Park 11

Figure 8 Distribution Frequency in both areas 13

Figure 9 Attendance total within time interval 13

Figure 10 Attendees correlated to PET Left: Matsudo Square, right: Matsudo Park 14

List of Tables

Table 1 Measuring Instruments 11

Table 2 PET Value Breakdown 12


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Introduction

The rapid change of global climate conditions increases the

consumption of energy and generates large amounts of pollution. The

effect of global warming, the increase of earths temperature forces

the inhabitants of urban areas to rely heavily on artificial air

condition methods which generate large amounts of Co2 emissions due to

the large energy consumption. There for that gives credit in promoting

global warming.

The awareness of this phenomenon has led responsible bodies

concerned with developing urban area to adopt methods to reduce the

effect of global warning causes. Architects are using different design

concepts to reduce reliance on artificial thermal conditioning methods

and promote passive systems.

In the process concerned with achieving passive thermal

conditioning, the focus was mainly on indoor closed spaces, neglecting

the outdoor open areas, but not until recently. Examples of increasing

focus by designers and developers on the outdoor space can be seen in

Bara Funda in Sao Paulo, Tokyo in Japan, Syracuse in New York, and

last but not least Hermosillo in Mexico.

The Aim of this paper is to examine the basics of outdoor

thermal conditioning in design literature, and then will look into two

case studies exhibiting the main points which had been took into

account for designing outdoor thermal conditioning in these areas, and

then will conclude with how effective are these interventions.


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Outdoor Thermal Conditioning

The Concept

Creating an acceptable thermal condition within a given space is

based on objective and subjective variables. They work in interact

together differently based on the place location and the nature of the

users.

Subjective variables are those elements that are defined by the

peoples behaviour based in their cultural and social characteristics

such as the acceptance level of temperature and wind speed within a

time interval or an area.

Objective variables are those elements that are set by the

physical attributes of the all the components that create spaces,

outdoor spaces in this case, such as materials colours and textures,

shapes and formations of masses, the function of the space, and last

but not least and most importantly static and dynamic features of

microclimate.

Ochoa and Marincic (2005) argued that the thermal comfort and

the energy impact on masses are neglected by designers. They suggested

that designers should attempt to address the last two points in and

work toward solving its issues.

Their suggesting is attributed to the following points of views

that;

1. Designers should acquire knowledge pertaining to a

series of fields as diverse than climatology, botany and

geography; however, this knowledge is not always expressed in a

language that they can adequately apply in their work.,

2. Since exterior spaces are normally not artificially

cooled or heated, there is no extra energy consumption directly

related with the outdoor thermal comfort. So developers of


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design tools and software have centred their efforts in thermal

design and efficient use of energy in building indoors,

banishing the landscape microclimatic design., and

3. Furthermore there is a lack of standards and

regulations for outdoors

Herrington and Vittum (1977) in their study of Syracuse in New

York had sought to set the variable related to human comfort in spaces

based on microclimate features within central urban areas.

They focused on the thermal exchange between the users of space

and their surroundings, by taking into account the physical attributes

of the materials and the physiological performance of the human body

in relation to heat transfer and exchange.

The Human Thermal Comfort

The status of the body which ensures the effectiveness of all

the internal functions after exposure to outdoor spaces temperature is

consider a thermal comfort area. This perception of this status is

completely subjective to the users state of mind and physical

condition. The different situations of the users scale the level of

comfort.

Herrington and Vittum (1977) have stated that Thermal stress is

created when the net loss of thermal energy from the subject's body

does not equal the production of heat by metabolism within the body

this mismatch depending on the outdoor temperature will cause either a

drop or increase in the internal temperature of the body. The body

respond to this in the form of skin respiration.

For idle stationed entities, the sensation of comfort results

from stabilising the body internal temperature to 98.6F (Herrington

and Vittum, 1977). Any excessive alteration to the surrounding


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temperature or the inner temperature may cause skin respiration which

is a thermal discomfort.

As for active moving entities, the level of comfort is based on

the body and surrounding air temperature for as long the exchange rate

between the body temperature and the surrounding air is at minimum.

Discomfort occurs in the case of excessive sweating (Herrington and

Vittum, 1977).

The Methodology

Basically to prepare a study regarding outdoor thermal

conditioning, it is important to note that it is based on empirical

research.

These should be carried out in designated times, the time which

considered vital to outdoor activity promotion.

Information is gathered from users subjects directly involved

within the designated area either by interviews or observation,

information such as the personal behaviour in the area, the users

physical characteristics of clothing, sex, age and their motives.

Microclimate information and pattern of air temperature, globe

temperature, surface temperature, relative humidity, wind speed,

incoming short wave radiation, and incoming long wave radiation should

be calculated and correlated with users behaviour in order to

establish a link to help understand what is needed to be done to

promote usage.


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Thermal Conditioning Case Study

Two case studies will be examined to demonstrate the how the

previously mentioned methodology had been implied and it was useful in

measuring and enhancing outdoor thermal conditioning.

The locations are in the city of Matsudo, Chiba prefecture,

Japan. The main characteristics of the area microclimate are a

temperate climate, warm and humid summers, and dry and relative mild

winter seasons (Thorsson, Honjo, Lindberg, Eliasson, and Lim, 2005).

The areas are Matsudo Central Park and Matsudo Station Square in

Matsudo central area.

Figure 2 Study Areas Location Map

(Thorsson, Honjo, Lindberg, Eliasson, and Lim, 2005)


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Matsudo Station Square

A one level elevated two squares next to Matsudo train station,

of an area of 50m by 40m paved with light coloured clinkers. It acts

as a point of gathering in the area of Central Matsudo. Its elevated

platform creates a pedestrians friendly area that connects the station

with the surrounding buildings.

Figure 2-3 Matsudo Square Platform and Street

(Thorssonet et al, 2005).

Matsudo Central Park

An open space area of 2.1 ha with two tennis courts and a

swimming pool, penetrated by walkways. A typical Japanese park located

east of Matsudo Station.

Figure 4 5 Matsudo Park Walkway and Lawn



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Empirical Research Method

The two researches were carried out simultaneously in the park

and the square, within the dates of March 12th till March 24th 2004

between 11.00 am and 3.00 pm. The process was consisting of structured

interviews, outdoor activity observations, and micrometeorological

measurements of both areas (Thorssonet et al, 2005).

For the structured interviews, it was carried out in Japanese

language a single interview lasted for an average period of 30 min,

addressing general information about the subjects such as: age,

clothing, visiting purpose, and desired times. Also it covered a

qualitative assessment of the areas by the subjects.

As for the outdoor activity observation, it was carried out

every 30 min, roughly 11 times per day. The areas were subdivided into

smaller sub areas to ease the observation process.

The data collected were about attendee number, sitting and

standing attendee in the sun and shade, and lastly personal behaviour

such as eating, reading, playing, smoking, and other actions. Also

passers through the site were taken into consideration.

Regarding the micrometeorological measurements, it was

calculated using two stations. Air temperature (Ta), globe temperature

(Tg), surface temperature (Ts), relative humidity (RH), wind speed (W),

incoming short wave radiation (S), and incoming long wave radiation

(L) values were calculated in the most vital parts of the two areas,

using their respective tools as shown in Table 1.


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Table 1 Measuring Instruments

Two fish eye shots were taken to create SVF analysis, one for

each area, with a measurement height of 1.1m (Thorssonet et al, 2005).

Figure 6-7 Right: Matsudo Square, Left: Matsudo Park


Matsudo Square scored 0.61 while Matsudo Park scored 0.58 due to the

vegetation layer presence (Thorssonet et al, 2005).

Wind speed was calculated at 2m height then it has been scaled

down using Sverdrups power law. Surface thermometers were used to

calculate surface temperature every 30 min (Thorssonet et al, 2005).

In attempt to investigate the thermal conditioning of the both

areas, air temperature (Ta), the mean radiant temperature (Tmrt), and

the physiological equivalent temperature (PET) values we correlated

altogether.


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By using computer calculation using the RayMan application,

which calculates (Tmrt) and (PET) based on urban areas parameters such

as (Ta) and humidity, time interval, and the Aledo of the nearby

surfaces.

The indicator used to express the PET value is explained in the

following table:

Table 2 PET Value Breakdown

The Results

The total number of respondents is 469, 219 at the park and 250

at the square. 74% were at the age between 21-65 years. 49.6% were

female and 50.4% were male.

Thermal Sensation

The distribution frequency of the thermal sensation resulting

from the carried interviews in the square shows that 25% of

respondents found it comfortable, 20% of respondents found it warm,

and 15% found it cold. (Thorssonet et al, 2005).


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Figure 8 Distribution Frequency in both areas

While the distribution frequency resulting from the interviews

carried in the park shows that, 30% of the respondents found it

comfortable, 15% of the respondent found it warm, and 20% of the

respondents found it cold. (Thorssonet et al, 2005).

Outdoor space Usage

Figure 9 Attendance total within time interval

Attendees of Matsudo Station were exceeding those of Matsudo

Park; an attendance peak could be noticed at 12.30 in Matsudo Park and

an attendance peak at 13.5 in Matsudo Square.


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Figure 10 Attendees correlated to PET

Left: Matsudo Square, right: Matsudo Park

By correlating the two outputs, PET frequency and the number of

attendees, we find that the number of attendees is not affected by the

PET conditions in the square case due to the fact that people dont

spend much time cause it is functioning as a joining hub between the

station and the surrounding areas and the users dont worry so much

about being discomforted.

On the contrary, the number of attendees on the park is

dramatically corresponds to the PET since the park is functioning as a

resting place and the duration of staying is more greater than that of

the square, people are becoming more subjective towards the PET

conditions.


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Conclusion

To conclude, the people behaviour, the place function, and the

climate characteristics dramatically affect the thermal conditioning

perception of the users.

The empirical method used to measure the performance of outdoor

open spaces is still traditional, but still it gives a clear and

comprehensive image that help in evaluating the efficiency of outdoor

spaces.

Outdoor spaces thermal conditioning is matter which is more

subjective rather than objective.


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References

HERRINGTON, L. P. and VITTUM, J. S. Human Thermal Comfort in Urban OutdoorSpaces, 1977

Thorsson, S., Honjo T. Lindberg, F. Eliasson, I. Lim, E. Thermal comfort conditions andpatterns of behaviour in outdoor urban spaces in Tokyo, Japan, 2005

Ochoa, J.M.I. and Marincic, I. Thermal comfort in urban spaces: The case of very warmand dry climate2005

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