Why is air tightness testing a requirement?

A BSRIA Presentation

By Andy McGrath

2Making buildings better

BSRIA Compliance Services

Topics

1. BSRIA

2. Air Tightness Testing & why is this a requirement

3. What causes Air Leakage

4. Common Air Leakage points

5. Part L Building Regulations

6. Testing Regimes


BSRIA Compliance ServicesBSRIA Compliance offers and provides a Single Source Solution for Airtightness, Ventilation and Acoustic Testing for Compliance with Building Regulations and Standards.

• Airtightness Testing – for Compliance Testing on Part L Building Regulations, (Part L1A & L2A) in England & Wales and equivalent regulations in Scotland (Section 6) & Northern Ireland (Part F).

• Sound Insulation Testing - for Compliance Testing on Part E Building Regulations, in England & Wales and Section 5 of the Scottish Building Standards.

• Ventilation Testing - for Compliance Testing on Part F Building Regulations, in England & Wales


BSRIA Compliance ServicesWhy Choose BSRIA Compliance ?

Choosing BSRIA to conduct your Compliance Testing, you are selecting an Organisation that you can trust and have confidence in, a team that you can rely on to provide the Service that you require.• Rapid response from Nationwide Team of Engineers, regionally located across England,

Wales, Scotland and Ireland to provide a Cost Effective Local Service.

• BSRIA are members of ATTMA, the Air Tightness & Measurement Association. The Accreditation / Registration of all our engineers can be checked /verified on the ATTMA registration site, to ensure that they are currently registered with the Test Authorities and the DCLG authorised Competent Persons scheme for Air Tightness Testing..

• BSRIA is UKAS accredited for Air Tightness Testing to CIBSE TM23, BS EN13829, ATTMA TSL1 & TSL2, which guarantees acceptance/recognition as an accredited Testing organisation by Building Control Authorities.



Air Tightness TestingWhy is this a Requirement for New Build Dwellings



There are 2 Main Reasons

A requirement to Comply with the Building Regulations Part L

To Reduce CO2 Emmissions and reduce Wasted Energy / Heat loss.


BSRIA Compliance ServicesAir Tightness Testing - Why is this a Requirement

Significant improvements in the Building Regulations, energy efficiency provisions, are seen as a major contributor towards achieving the target of a 20% reduction in carbon emissions.

Compliance with the Building Regulations would, lead to / equate to an improvement in the energy efficiency of new Dwellings (and a reduction in the carbon emissions they would otherwise produce) of around 25%.


BSRIA Compliance ServicesWhy is this a Requirement

Prior to the 2006 Building Regulations, It was found that New Homes were emitting 6000 tonnes MORE Carbon dioxide each year, than they should be, in comparison to if the homes were compliant with the foreseen airtightness standards.

This was the finding of a report undertaken on behalf of the Energy Saving Trust, which called for the inclusion of mandatory pressure testing in the Part L Building Regulations.

Non complying homes emit on average 14% more carbon dioxide than complying homes.

With about one million new homes set to be built over the next five years, more than 30,000 tonnes of carbon dioxide emissions could be saved by carrying out “as-built testing”.

It was these facts that instigated Air Tightness Testing being incorporated into the Building Regulations.


Why Is Reducing Air Leakage Important?

■ Heating buildings involves burning fossil fuels and producing CO2 emissions

■ CO2 is a greenhouse gas – it contributes to global warming■ Reduced air leakage, results in reduced heating energy use■ The purpose of reducing air leakage is to reduce CO2

emissions, reduce heating bills, and improve occupant comfort


BSRIA Compliance ServicesWhat is Air LeakageAir leakage is the uncontrolled flow of air through gaps and cracks in the fabric of a building (sometimes referred to as infiltration or draughts).

This is not to be confused with ventilation, which is the controlled flow of air into and out of the building through purpose built ventilators that are required for the comfort and safety of the occupants.

Too much air leakage leads to unnecessary heat loss and discomfort to the occupants from cold draughts.

It is expressed in m3/(h.m2) @ 50 PaThe worst allowable design air permeability is 10 m3/(h.m2) @ 50 Pa


What is Air Leakage? The increasing need for higher energy efficiency in buildings and the need in the future to demonstrate compliance with more stringent Building Regulations targets, means that airtightness has become a major performance issue.

The aim should be to ‘Build tight – ventilate right’. Taking this approach means that buildings cannot be too airtight, however it is essential to ensure appropriate ventilation rates are achieved through purpose built ventilation openings in accordance with Part F.


What causes Air Leakage? ■ Wind blowing against or across a buildingWind against the dwelling causes pressure differences between the inside and outside. Air is drawn into the dwelling through gaps on the windward face (infiltration) and leaves the dwelling on the leeward face (exfiltration)

■ Warm air rising within a building (the stack effect)Warm indoor air is more buoyant than colder outside air (buoyant air rises by convection). This rising effect draws in cooler air from outside (infiltration) which is felt as cold draughts inside. The rising effect increases the pressure inside the dwelling which pushes warm air out of cracks and gaps in the envelope (exfiltration). It is worsened when it is very cold outside and warm inside.


Common Air Leakage Points by Classification


1 Junction lower floor / vertical wall2 Junction window sill / vertical wall3 Junction window lintel / vertical wall4 Junction window reveal / vertical wall (horizontal view)5 Vertical wall (Cross section)6 Perforation vertical wall7 Junction top floor / vertical wall8 Penetration of top floor9 Junction French window / vertical wall10 Junction inclined roof / vertical wall11 Penetration inclined roof12 Junction inclined roof / roof ridge13 Junction inclined roof / window14 Junction rolling blind / vertical wall15 Junction intermediate floor/vertical wall16Junction exterior door lintel/vertical wall17 Junction exterior door sill / sill18 Penetration lower floor / crawlspace or basement19 Junction service shaft / access door20 Junction internal wall/intermediate floor

Common leakage points are listed in the Figure below and explained adjacent:


Why is Reducing air leakage important?

■ Air leakage in buildings through cracks around doors, window frames, electrical and plumbing connections etc. accounts for a significant proportion of heat loss.

■ With recent improvements in the insulation of walls and glazing, this proportion has become more significant.

■ Designers used to assume a value for airtightness for the purpose of calculating heat losses and predicting energy use – now it can be measured



The 2008 Climate Change Act established the world’s first legally binding climate change target. The aim is to reduce the UK’s greenhouse gas emissions by at least 80% (from the 1990 baseline) by 2050.

In 2012, direct buildings emissions (mainly from the use of gas for heating) accounted for 37% of UK greenhouse gas emissions (91 MtCO2). Buildings also were responsible for 67% of electricity consumption and related (i.e. indirect) emissions. The residential sector accounted for 66% of overall buildings CO2 emissions (134 MtCO2), 55% of which were direct emissions (mainly from gas).

Air Tightness Testing can reduce the amount of Carbon Emissions from New Dwellings

http://www.legislation.gov.uk/ukpga/2008/27/contents


Building Regulations


A little history…

• The 2002 UK Energy White Paper gave a national target of a 20% reduction in CO2 emissions below 1990 levels by 2010

• Also in 2002, the EU issued the Energy Performance of Buildings Directive

• As a result Building Regulations were upgraded in 2006 (2007 in Scotland), now incorporating Energy Performance including CO2 emissions calculations and airtightness testing.


Building Regulations• Building Regulations are legal requirements• Guidance on how to meet the Building Regulations in

common situations is given in:– Approved Documents (England & Wales)– Technical Handbooks (Scotland)– Technical Booklets (Northern Ireland)– Technical Guidance Documents (Republic of Ireland)

• England and Wales have had separate regulations since 2013, however as far as carrying out airtightness testing is concerned, the only difference is Wales has stricter energy targets, so design air permeability's are likely to be lower


• The energy assessor calculates the Building or Dwelling carbon dioxide Emissions Rate (BER / DER), which must be less than the Target carbon dioxide Emissions Rate (TER)

• The energy assessor uses SAP for dwellings, SBEM or a Dynamic Simulation Model for non-dwellings

• Specifying a low Design Air Permeability will help with achieving a BER/DER lower than the TER

• The same calculation method is used to produce the Energy Performance Certificate, (once the measured Air Permeability figure has been entered back into the SAP Calculation).

Energy Calculations in Building Regs


England / WalesBuilding Regulations

• English Building Regs and Approved Documents can be downloaded from www.planningportal.gov.uk,

• Mandatory airtightness testing was introduced in 2006• Approved Documents were updated in 2010 – these came into

effect in October 2010 but only for building work started or notified after that date

• The 2010 update resulted in changes to airtightness test methods and sampling procedures

http://www.planningportal.gov.uk/



• Building Regulations and Approved Documents were

updated in England in 2013 and Wales in 2014 – these came into effect in April 2014 (England) and July 2014 (Wales) but only for building work started or notified after that date

• No changes were made to airtightness test methods or sampling procedures in 2013/2014, however it’s worth noting which version of the Building Regulations the test is required to be conducted under, as this could determine the number of tests required.


Step changes in energy use• In 2010, the TER reduced by 25% compared with dwellings

built under 2006 Building Regulations• In 2013, in England, the TER reduced by a further 6% for

dwellings and 9% for non-dwellings. • In 2014, in Wales, the TER reduced by a further 8% for

dwellings and 20% for non-dwellings• As a way of achieving these lower emissions, many

designers will select lower design air permeability's• However the worst allowable design air permeability

remains unchanged at 10 m3/(h.m2) @ 50 Pa




The Building Regulations require that:• “Reasonable provision” is made for the conservation of fuel

and power whenever building work is carried out• Airtightness testing is carried out on new dwellings in

accordance with ATTMA TSL1 and new non-dwellings in accordance with ATTMA TSL2

• Building control is authorised to accept certificates from ATTMA registered testers

• Airtightness test certificates are to be provided to building control.


Approved Document L1A (Dwellings)

How much testing is needed?Part L requires a minimum sample testing and sampling rates are applied to groups of dwellings that are defined as similar based on specific criteria described within the Approved Document.

Part L 2010 and 2013 increased the minimum amount of testing required to 3 tests or 50% of each dwelling type, whichever is less. The criteria for defining similar dwelling types has also expanded such that there are now likely to be more tests required per development than was the case under Part L 2006.



What is a dwelling type?The following are always considered different types: Detached houses Mid-terrace houses End-terrace houses Semi-detached houses Ground floor flats Mid-floor flats Top-floor flats



What is a dwelling type?

Furthermore, for dwellings to be considered of the same type: They must have the same number of storeys They must have the same design air permeability They must have similar adjacencies to unheated spaces

e.g. stairwells, unheated garages They must have the same principal construction details



What is a dwelling type?

Furthermore, for dwellings to be considered of the same type: They must have envelope areas that differ by less than

10% The difference between the smallest and largest number of

significant penetrations (i.e. windows, doors, flues, chimneys, supply / exhaust terminals and waste water pipes) must be no more than one



What about dwellings that don’t get tested?

• To pass the test, the assessed air permeability must be less than the design air permeability

• Where the dwelling has been tested, the assessed air permeability is the measured air permeability



Where the dwelling has not been tested, but others of the same type have, the assessed air permeability is the average measured air permeability from dwellings that were tested, plus 2 m3/(h.m2)@50 Pa

Note that this is in effect a penalty, although it is referred to as a Confidence Factor and it may result in designers demanding that all units get tested


What about dwellings that don’t get tested?


In the case of a dwelling that is not tested, the assessed air permeability is equal to the average of the measured air permeability of dwellings of that type that were tested, plus 2 m³/(h.m²) @ 50 Pa.

This means that the test results for all the dwellings tested will need to be ‘2.00’ less than the design air permeability in SAP or each plot will need to be tested in its own right.



The final DER/TER calculation for untested dwellings will need to use an “assessed air permeability” which is the average result of the tested dwellings plus 2 m³/(h.m²) @ 50 Pa.

Therefore unless every instance of the same dwelling type is pressure tested, the actual measured air permeability of the tested dwellings needs to be at least 2 m³/(h.m²) @ 50 Pa less than the design air permeability.



Dwellings that don’t get tested: Sample Testing example:You have been asked to test 4 identical dwellings, with a design air permeability of 6m³/(h.m²) @ 50Pa

Only 2 dwellings are required to be tested (50%), (3 tests or 50% of each dwelling type, whichever is less). These dwellings now have to be tested to 4m³/(h.m²) @ 50Pa, (2 less than the DAP) and you obtain test results of 4m³/(h.m²) @ 50Pa and 5m³/(h.m²) @ 50Pa



Although both of these dwellings pass the test, (under a 100% testing Regime), using their average performance, to determine the assessed air permeability for the other two dwellings which are not being tested, (using the measured average), the assessed air permeability is now equating to 6.5m³/(h.m²) @ 50Pa, (average result of 4.5 plus 2),

so both of the houses (that have not been tested) cannot use the assessed air permeability, for the tested houses, as it is too high.



In order to get all the dwellings to pass with only one additional test, the next dwelling to be tested will now need to achieve a result of no more than 3m³/(h.m²) @ 50Pa in order to push the average down below the required 4m³/(h.m²) @ 50Pa

In relation to this example, it can be seen that it may be easier to test both remaining dwellings, which will equate to a 100% test regime overall.



It should also be noted that if we refer to the example used,

if we are testing plots with Air Permeabilities down in the region of 4m³/(h.m²) @ 50Pa,

then this also brings into account Ventilation systems as you will have to ensure that the ventilation system is suitable/relevant to a dwelling with this level of air tightness.



If satisfactory performance is not achieved with any of the sample properties tested, then remedial measures should be carried out on the dwelling and new tests carried out until the dwelling type achieves the criteria set out. Failed test results must still be submitted to Building Control.

In addition, a further dwelling of the same dwelling type should be tested, thereby increasing the overall sample size and this applies in relation to each dwelling that fails the test criteria and as seen from the example, unless the latest dwelling to be tested achieves an assessed air permeability significantly below its design permeability, the average will not be reduced sufficiently and therefore the number of dwellings to be tested will be increased.



With a 16% to 40% improvement in the Target Emission Rate (TER) under the 2010 revisions, it is unlikely that buildings will be able to achieve the overall targets for energy improvement without significantly improving air tightness.

Designers/builders will therefore need to weigh up whether to significantly improve air tightness performance, or to incur potentially more substantial costs by improving other factors that influence the SAP calculations, e.g. heating, renewable energy sources, etc. It is the SAP Calculations that determine the Air Permeability figure.



On this basis typical air testing targets are improving from 6-10, down to the region of 3-6 m³/(h.m²)@ 50Pa

With the general lowering of Air Permeability figures and taking into consideration the penalties associated with Sample Testing. Many residential developers are for these reasons, opting for 100% testing regimes.



SummaryAir Tightness Testing – Is it necessary, Who does this Benefit.

It is necessary, in order to reduce wasted Energy and Carbon Emissions, to assist with making Dwellings more Energy Efficient.It provides a Quantitive analysis, (an actual measurement) regarding the Building Performance.It is also a requirement for Compliance with Building Regulations Part L.

It benefits us all,• You, Me• The Environment• The House Buyer

Why is air tightness testing a requirement?

Engineering

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