Frequently Asked Questions

Air Tightness/Air Leakage Testing – A Definition

Air leakage testing – the resistance of the building envelope to inward or outward air leakage. Excessive air leakage testing results in increased energy consumption and a drafty cold building. Air leakage testing is driven by differential pressures, across the building envelope. The mechanisms that create these differences in pressure are the combined effects of – stack (internal warm air rises), external wind (inducing +ve and –ve pressures on the envelope) and mechanical ventilation systems. We at APT we are one of the foremost Air leakage testing companies currently practicing under part L

The New Building Regulations Part L 

Note – Part L1 applies to dwellings, Part L2 to non – domestic buildings. Part L1A and L2A refer to new buildings and L1B and L2B to refurbishments. As one of the leading air leakage testing companies we can quickly and accurately explain what category your building fall in to

The reason the New Building Regulations Part L include for air leakage testing?

The Government is committed to reduce CO2 emissions from energy consumption by 20% by the year 2010. Many of the buildings constructed today (both dwellings and commercial) consume more energy than necessary. Two major factors in the design and performance of building fabric which affect energy consumption are, air leakage testing and continuity of insulation, APT can quickly help your company achieve the required results as one of the leading air leakage companies in the business

There are also substantial commercial benefits to building owners that will accrue over the life time of the building. Reduced energy costs provide clients with real cash incentives to achieve airtight buildings after air leakage testing. Other benefits are gained from increased comfort for building users, office staff and / or customers. Although difficult to total, these are tangible benefits to the client and the welfare of their respective personnel.

When did the latest Part L of the building Regulations come into force?

Air Leakage Testing became a requirement under Part L in April 2002 with a recent update in April 2006. Now, all buildings that pass through the planning and building control processes have to comply with Part L this in turn requires YOU the client/contractor to undertake an air leakage test by  reputable air leakage companies. The Government is looking to tighten up the regulations and further updates are due in 2010, this may require all buildings to undertake air leakage testing.  European Legislation has also been enacted, tightening the use of energy in buildings. This was introduced in January 2006 through the European Performance in Buildings Directive.

Rules To Ensure Part L Is Met

All parties involved on the project from the client, contractor and consultants to all site staff and operatives and off site suppliers need to understand the concepts of air tightness/air leakage testing and how they affect the part of the project they are involved with. It only takes one part of the building to be suffer from air leakage to ensure a failure to comply, which can lead to costly remedial works and time delays. A real effort needs to be made to educate everyone involved and ensure that a team effort is made to avoid a failure being issued by the air leakage company.

ALL buildings require designs to incorporate ‘robust details’ to ensure air tightness, continuity of insulation and potential problems with thermal bridging are addressed.

For non domestic buildings, carry out an air leakage testing to ATTMA TS1.

For buildings < 500 m² gross floor area, assume an air permeability rate of 15 to calculate the BER or carry out an air leakage test.

Remember that the maximum air permeability rate is 10 m³/h/m² at 50 Pascals. However, the air permeability target may have been set tighter so that the carbon rating is met!! Please phone APT if you are unsure, we can help you identify your required air leakage rate using our proactive approach as one of the leading air leakage companies

Changes between Part L 2006 and 2002 for Commercial and Domestic Buildings, New and Existing.

Key Changes for New Commercial Buildings Part L2A

Obtaining compliance is now a five-step procedure.

1. Designers will need to:

·         Show a home’s predicted CO2 emission rate will not be greater than the target emission rate.

·         Ensure the performance of the building’s fabric, heating, hot water and lighting meets the minimum values set out in the document.

·         Introduce passive measures to prevent homes overheating.

·         Ensure construction is consistent with the design.

·         Provide the occupier with information to order to allow the building to be operated as efficiently as possible.

2. Dwellings now require testing by air leakage companies

The air permeability of the envelope should be no greater than 10m³/h/m².

3. Dwellings will have to produce 20% less CO2 than they do under the existing regulations.
A carbon comparison must be produced to show how a home’s predicted CO2 emission rate compares to target emission rating based on a national dwelling, compliant with the 2002 regulations. A fuel factor can be applied to the rating if LGP, oil mains electricity or solid fuel is used, making it easier to comply when using these fuels than their carbon content would otherwise allow. So, with careful design, electric heating can still be used in apartment blocks. Please phone APT if you are unsure, we can help you identify your required air leakage rate using our proactive approach as one of the leading air leakage companies

4. There are two routes to compliance for apartments.
A penthouse does not have to comply with the carbon emission rate provided the remaining dwellings can compensate, since the compliance for apartment blocks can be demonstrated either as individual SAP calculations for each dwelling or as an area-weighted average for all dwellings in the building.

5. A report should be provided to Building Control
Air pressure testing will identify the features that deliver the CO2 reduction. At completion, additional schedules covering lighting, robust details and non-accredited details are required, together with evidence that air permeability standards have been achieved by passing the air leakage test, systems have been commissioned and operating instructions issued. As a leading air leakage company APT provide a fully compliant air leakage report

How Existing Commercial Buildings Will Be Affected Part L2B

1. More work is subject to the regulations
The rules will apply to: an extension, a change of use or alteration, provision of a controlled fitting or service and a provision of a thermal element.

2. The route to compliance for an extension has not changed
The elemental route to compliance remains for extensions and cases where the use of a building has changed.

3. Individual elements must meet specific standards
Provisions apply to acceptable performance standards for windows, heating and hot water systems, lighting, insulation of pipes, ducts and mechanical cooling systems, commissioning and the provision of information.

4. Entire elements may need to be upgraded
When 25% of a thermal element, such as a roof is upgraded, the entire element should be upgraded to the latest elemental standards if pay back for the work can be achieved within 15 years. If not, it should be upgraded to a standard that does achieve payback within that time.

5. Historic buildings
Energy efficiency measures should be incorporates where they will not prejudice the character of the building.

If you are unsure which category your building falls into phone  APT the most proactive air leakage company for further information

Key Changes for New Domestic Buildings Part L1A

1. Obtaining compliance is now a five step procedure

·         The predicted building CO2 emission rate should be no greater than the target rate.

·         The performance of the building fabric, heating and hot water and lighting should comply with the minimum limits in the document

·         Passive measures should be included to prevent overheating for areas without cooling.

·         The building should be built as designed.

·         Provision should be made to enable energy efficient operation.

2. Air Permeability /air leakage testing companies
Air Leakage Tests are required for every building that incorporates a floor area greater than 500m²

3. Overheating
Designers must demonstrate that the combined solar and casual heat gains do not exceed W/m² or that the temperature does not exceed 28C for more than 20 hours a year spaces with no comfort cooling.

4. Fully glazed buildings will comply
A typical mechanically cooled and ventilated building, 40% glazed and built to 2002 standards can comply through a combination of omission of roof lights, improvement in double glazing specification and lighting controls. An equivalent building with 100% glazed facade could comply with a similar improvement strategy, but with an additional improvement in the chillier seasonal efficiency.

5. Calculating energy consumption
Two calculations are required: a preliminary one, as part of the design commission, and a final calculation demonstrating compliance based on ‘as constructed’ information, incorporating any performance changes made during construction.


How Existing Domestic Buildings Will Be Affected Part L1B

1. More work carried out to existing buildings is subject to the regulations
An extension, material change of use, material alteration, the provision or extension of a controlled service or fitting and the renovation of a thermal element are all now subject to the regulations. Phone Air pressure testing if you have any queries e.g. to clarify if your property requires Air leakage testing

2. Consequential improvements
Work to existing heating or cooling systems, windows or walls below the element standards must be upgraded, provided it is technically, functionally and economically feasible.

3. The 10% rule
The requirement for consequential work is limited to 10% of the value of the principle works. The following elements are all subject to the 10% rule: any heating, cooling or air handling system older than 15 years should be replaces by new plant and improved controls; any inefficient lighting system serving more than 100m² should be upgraded; energy metering should be installed; and if the renewable energy contribution is less than 100%, the system upgraded provided payback is less then seven years.

4. Extensions
Elemental standards are given for the building fabric and windows in extensions. There is some flexibility allowed, provided the heat loss for area weighted U-values is no greater than the equivalent compliant extension. Extensions over 100m² and greater than 25% of the floor area of the existing part of the building come under Approved Document L2A. Phone Air pressure testing if you have any queries e.g. to clarify if your property requires Air leakage testing

5. Controlled fittings or services

Compliance is largely elemental, with specific minimum standards to be achieved. There are additional requirements governing commissioning, the provision of the sub-meters and log books

Check List to Identify Suitably Qualified Air leakage Testing Companies

 

1.       Check the envelope area calculations refer to the whole building envelope and that this is the envelope that has needs to be tested by the air leakage company.
Has the envelope area been independently verified  - by the architect? Check that the test has been carried out on the same envelope criteria – i.e. no areas have been excluded for the air leakage test and included in the calculations, if so this must be clarified to the air leakage company

2.       Check the envelope area calculations refer to the whole building envelope and that this is the envelope that has been actually air leakage tested by the air leakage company
Has the envelope area been independently verified  - by the architect?

3.       Check that the test has been carried out on the same envelope criteria – i.e. no areas have been excluded for the air leakage test and included in the calculations.

4.       The whole building should be air leakage tested wherever possible - Not only is the result more accurate but it increases the chance of the test passing and gaining compliance. If areas have been excluded, are the reasons valid? If you are not sure inform the air leakage company undertaking the Air leakage test

5.       Check that temporary sealing has only been applied to H and V equipment and other permanently open natural ventilations; otherwise you will fail the air leakage test. Contact the  air leakage company if you are unsure what vents etc require sealing

6.       During the air leakage testing, if possible be inside the building and check-

·         internal doors are kept open

·         no additional temporary seals have been added

·         External windows and doors stay closed

·         Ambient conditions – wind speed should ideally be a maximum 13 mph

6.    The following readings and values should be checked. Any readings outside the parameters detailed below indicate the test has been carried out incorrectly and the test should be carried out again.

·         Minimum 6 number readings taken.

·         Or 5 x the zero flow pressure difference.

·         The minimum pressure differential should be = 10 Pascals and maximum pressure differential = 35 Pascals.

·         Correlation coefficient >0.98, any lower than 0.98 indicates the readings are too far spread.

·         N has to lie within the range of 0.5 - 1.0 values outside of this range indicate that the test has not been carried out properly.

Check the procedures for the air leakage testing if the building is large and multi-cellular or over storeys tall. Phone APT (the most proactive air leakage company) if you are unsure of your air leakage requirements

Why have major retailers have driven air leakage testing levels down to best practice level in the last 12 years?

Commercial Benefits to the Building Owner and Client b y working with Air Leakage Companies

One reason only – there are substantial commercial benefits to having an airtight building and retailers are accruing those benefits for the life time of the building stock. Working with a commencement air leakage company will ensure huge future savings

A typical example of the real benefits that can be realised was seen on an existing retail store that was sealed in February 1997. The ambient temperature in the store was raised by 5°C, after the store had been air sealed.

Typical air leakage permeability rates of 3 m³/h/m² have been obtained on new retail stores and 5 m³/h/m² on existing stores. These levels of air tightness have been achieved by incremental improvement over a number of years and effort by all parties involved with the projects. As a premier air leakage company air pressure testing will help you to keep your future fuel bills to a minimum

The additional costs to clients on new build retail stores is < 0.5% of the total spend.

The real benefits obtained from achieving a good level of air tightness can be summarised as;

·         Lower energy costs for the life time of the building

·         Lower initial capital costs due to down sizing of plant and equipment

·         Air leakage testing can act as performance tests for fire compartments as well as external envelopes

·         The environment within the building becomes less drafty and potentially warmer. Productivity of staff could be raised significantly - a happy worker is a productive worker!

·         The risk of interstitial condensation within the building fabric is minimised, if the building fabric is built to an air tightness standard. Degradation should therefore be reduced in the long term.

Different types of buildings require different levels of air leakage testing. Air conditioned buildings should be tighter than naturally ventilated ones. Archives, cold rooms and museums will all require to be much tighter to ensure the specification levels for the control of humidity, heat loss and the ingress of pollutants are met. Phone APT if you unsure of your air leakage specification

What is the Good Practice Guidelines for Different Building Types?

Good Practice Guidelines for Different Building Types
The following figures are recommended air tightness specifications for various building types as set out in CIBSE TM 23.

Air leakage index

Air Permeability

m³/h/m² at 50 Pa

Practice

Good

Best

Good

Best

Building Type

 

 

 

 

Office - naturally ventillated

10.0

5.0

7.0

3.5

Offices - balanced mech vent.

5.0

2.5

3.5

2.0

Superstores

5.0

2.0

3.0

1.5

Industrial

15.0

3.5

10.0

2.0

Dwellings

15.0

8.0

10.0

5.0

What is the Theory Of Air Tightness, Air Leakage Testing and Air Sealing Measures? Ask your air leakage company now!

Theory Of Air Tightness, Air Leakage Testing and Air Sealing Measures

Terminology

Air tightness / air permeability (air leakage testing) – defined as the resistance of the building envelope to inward or outward air permeation. Air leakage is driven by pressure differentials between inside and outside a building caused by the wind, stack effect and mechanical ventilation systems. Excessive air leakage leads to increased energy consumption, increased drafts within the building and increased risks of condensation within the building fabric. For the client, air leakage testing is physically felt with cold drafts caused by the uncontrolled movement of air into or out of a building. Cold drafts/air leakage  usually cause complaints from building users! Working alongside an air leakage company will help you alleviate any future complaints

Air barrier or air seal line – the physical components that make up the airtight envelope of the building. The air barrier needs to be continuous around the whole envelope – roof, walls and ground floors, durable and maintainable in the long term. The air seal line should be drawn on construction drawings to communicate the strategy to all relevant along with your practicing air leakage company.

Air tightness test or air leakage testing – the building is air pressure tested by connecting a fan and measuring the airflow rates required to keep the building at various positive or negative pressures. The air leakage company should try to keep site disruption to a minimum

Air permeability – expressed as the amount of air leakage in cubic metres, per hour, per square metre of envelope at a nominal pressure differential of 50 Pascals, between inside and outside the building envelope.

Q50 – air flow rate required to pressurise the building envelope to 50 Pascals, measured unit - cubic metres per second. The air leakage company should always try to achieve this air flow

Information for the Client

Rules to Ensure Part L Is Met Ensure air tightness is thought about at the concept stage of the project and designed in from the start.

Ensure that all materials and components used for air tightness test purposes have a similar specification and longevity, as all others used on the project. There is no reason that buildings constructed to an airtight standard should be stuffy for occupiers or be at greater risk from condensation. The rule is; build tight – ventilate right. Is  there a risk from making a building envelope too airtight?

No. Part L is meant to control the amount of uncontrolled air leakage through the building fabric, not the amount of controlled ventilation. Ask your air leakage company now if you are unsure or need extra info

Is the target air permeability rate achievable?

The target air leakage/permeability rate of 10 m³/h/m², set down in Part L is achievable when current best practice for buildings is around 2 m³/h/m². However, if no regard is taken to air tightness, it is probable that Part L will not be complied with, your air leakage company should help you through the air leakage process

How expensive will it be?

Additional building costs may amount to 0.5%. This ignores cost savings from down sizing heating plant and the life time reduction in energy costs.

When To Get Worried

When a party claims that air leakage problems will be sorted out after the first air leakage test and will be remedied then. Air Pressure Testing’s golden rule is that it costs considerably more to put right second time, rather than doing it right first time. Ensure that maintenance procedures take air leakage into account. Degradation or damage to air tight elements or components needs to be minimised over the long term. We have witnessed how simple it is for an electrician to punch a large hole through a wall, thereby increasing the air permeability figure significantly enough for users of the building to complain about an increase in drafts. Your air leakage company should be able to undertake a survey prior to the first air leakage test to ensure the chance of air leakage failure is kept to an absolute minimum

Information for the Architect

Golden Rules To Ensure Part L is Met

Designing airtight buildings is the only means of ensuring long term, low air leakage testi performance. Build tight – ventilate right. The objective is to minimise uncontrolled air leakage whilst maintaining controlled ventilation. Ensure the air barrier is based on structural elements, wherever possible. Condensation risk will be minimised if the air barrier or seal envelope is correctly positioned, which depends on the make up of the construction element itself. Generally, it should be placed on the warm side of the insulation layer. It is also important for the insulation layer to be continuous and to bear in mind that excessive cold air moving around loose or misplaced insulation can lead to interstitial condensation.

Ensure that the air leakage testing is carried out by a member of the British Institute of Non Destructive Testing The DCLG recognises members as being ‘suitably qualified’ and ‘competent’ companies to carry out air leakage testing. APT is one such air leakage company

What needs air sealing on site?

Careful consideration is needed on all structural elements. For instance pre-cast concrete floors may look airtight, but consider air leakage along open voids through the slab into cavities in external walls! Also think about non-structural elements such as roof liner sheets or T and G boarding. A 1mm gap along each joint adds up to a considerable area for air to leak through. Please download Air Pressure Testings helpful checklist. If you are unsure of typical air leakage areas phone your favored air leakage company

Where can I access reference to standard details?

·         The Stationery Office – Dwellings BRE Good Building Guides

·         Kingspan

·         SEDA

·         The Stationery Office

·         MCRMA

When To Get Worried

Any supplier of materials or components who can not state the air leakage rate (permeability) of their product per meter square, as tested to BS / EN standards. Be forewarned, material suppliers who states their components are air tight. NO materials are perfectly airtight, particularly after installation on site!

Using dry lining or vapour barrier as the air barrier is possible with good detailing. However, a high level of site supervision is required to ensure all junctions are air tight and that the lining is not damaged.

Please note: Perforated liner sheets are NOT suitable as an air seal line.

If you have any concerns, request that the material or component under goes an air leakage test. Many air leakage companies can offer this air testing sampling service

 

Information for the Main Contractor

Golden Rules to Ensure Part L Is Met

Ensure that good, sound building practice is delivered so that the building is airtight and therefore doesn’t fail the air leakage testing. If the building is not airtight, the air leakage permeability target of 10 m3/h/m2 will be exceeded. The end user (– client) may also find that ventilation is inadequate and may complain of drafts at times of the year when the building is difficult to heat or cool, an example of this was bought to our attention when a primary school could not achieve their minimum operating temperature due to massive amounts of Air Leakage, this was due to poor design detailing around the eaves, this resulted in the children being sent home every time the temperature dropped below the minimum requirement. APT is the  leading air leakage company for highlighting your air leakage areas

State clearly in all pricing enquiries the air tightness specification and ask for details of compliance including specifications, method statements, quality audits, etc, etc. Ensure a person on site is nominated to control and audit all aspects of air tightness works, through out the contract period on site. Do not enclose or cover cavities or gaps before the air tightness works have been quality assured otherwise the chance of an air leakage testing failure will be greatly increase. As above APT is the  leading air leakage company for highlighting your air leakage areas

How can a large number of suppliers and sub contractors be controlled to ensure air leakage issues are addressed prior to air leakage testing?

Use similar methods to those used at present to control all aspects of contracts specification, method statements, quality management systems, etc. Problems generally occur when responsibilities for each element or package of work are not clearly defined and agreed, prior to site work starting.

If the air leakage test fails, how can air leakage paths be found? As a leading air leakage company Air Pressure Testing uses a variety of techniques can be used to identify leakage paths – these include;

·         Feeling for drafts adjacent to the air barrier, whilst the building is being air leakage tested. It is useful if the air test fan unit can pressurise and de-pressurise buildings so that drafts can be felt for on both the internal and external faces of the air barrier during air leakage testing.

·         Running localised smoke tests using a hand held directional smoke generator.

·         Running a smoke test on the whole building and undertaking a full photographic survey.

·         Carrying out a Thermographic survey

·         Physically checking over the risk areas looking for holes, gaps, etc

Which building components are particularly prone to air leakage?

Apart from the obvious - unsealed block work, hollow concrete beams or floor planks, joints/junctions in curtain walling and dry lining systems, hollow frames/mullions/transoms, hollow steel sections penetrating the roof or walls, lap joints on roof liner sheets or T & G boarding - to name a few! Note there are many more areas that are prone to air leakage, as a leading air leakage company Air pressure testing can identify all potential air leakage areas to ensure you pass first time!

What area of leakage holes am I looking for?

Dividing Q50 by 5.5 gives an approximate figure for the total leakage area in metres square. For example; if Q50 = 37 m³/s the total leakage area = 6.7 m².  Treat this figure with respect and care as the visual hole seen on the air seal line is not always the actual area that air is ultimately leaking from – the final leakage hole could be a lot smaller. Your air leakage company can help clarify these hard to find areas of air leakage.

 

Envelope
Area (m2)

Leakage Rates (m3/hr at 50Pa)

Envelope
Area (m2)

5

7.5

10

15

20

25

2000

0.51

0.76

1.01

1.52

2.03

2.54

5000

1.27

1.90

2.54

3.80

5.07

6.34

7500

1.90

2.85

3.80

5.71

7.61

9.51

10000

2.54

3.80

5.07

7.61

10.14

12.68

12500

3.17

4.75

6.34

9.51

12.68

15.85

15000

3.80

5.71

7.61

11.41

15.21

19.02

20000

5.07

7.61

10.14

15.21

20.29

25.36

Leakage Rates (m3/hr) by Area (m2)

 

When To Get Worried

Any sub contract package is proposing to use gaffer tape or plastic sheeting to air seal works. Can we do the air leakage testing next Tuesday, if the roof plant comes tomorrow and the fitters come in on Sunday to install it? NO! Plan ahead and ensure the building is ready for the air leakage test. Ensure the size – flow rate of the fan is adequate for the job. Ask for calculations to back this up. All competent air leakage companies will not undertake a test if gaffer tape etc is being used as a long term barrier against air leakage.

Information for Building Services Consultants

Golden Rules To Ensure Part L is Met

Ventilate right – the main contractor should build the envelope tight. This will enable the design, specification and sizing of the heating and ventilation system to be carried out with confidence.  Fresh air openings in the envelope constitute massive air leakage paths and will ensure buildings fail the air leakage testing.  Check the envelope area is correct. All competent air leakage companies will undertake the checking of the building envelope as it is critical the size is correct otherwise it will effect the overall result and could end in a air leakage failure!

What BS or EN standards are air leakage pressure tests carried out to? 

ATTMA TS1 & BS EN 13829:2001(1) Thermal Performance of Buildings: Determination of air permeability of buildings – Fan pressurisation method. All competent air leakage companies will undertake the air leakage testing to the above specification.

How can air permeability standards be expressed as air changes per hour – each at a test pressure of 50 Pascals?

For a moderately sized single storey building which complies with Part L, Qleakage = <10 m³/h/m², the average ventilation rate will be approximately 0.3 ach. The ventilation rate in ach can be approximately estimated as A/(6*S) ach where A = Area of walls, roof and ground floor and S = area of walls and roof.

What is the heat loss due to air leakage?

Qleakage = rCp  *  V * n / 3600    W/K     where rCp heat capacity of air, V volume of building m³ and n
                                                                 is the ventilation rate in air changes per hour - ach.

What are typical levels of savings in terms of energy usage?

For an industrial building with a floor area of 5000 m2, currently built without air tightness considerations; air permeability can be > 14 m³/h/m². This equates to a hole in the roof of approximately 5 m²!!

If the air permeability can be reduced to 8 m³/h/m², which comfortably passes Part L, then the energy saving could equal > 60,000 kWh per annum. NOTE. Current best practice for industrial type buildings in regards of air tightness is an air permeability figure of 2 m³/h/m². Air pressure testing has undertaken air leakage testing where the results have been below 1 m3/h/m2 so these figures are easily achievable.

How can complicated service penetrations be sealed?

Services can be routed through ducts inside the building envelope. Sealing multiple service penetrations is awkward but similar principles to those used to seal penetrations through fire walls and plant room slabs should be used. As leading air leakage company air pressure testing can undertake the sealing of all penetrations prior to the air leakage test.

How can the flow rate for the air leakage pressure test be specified in terms of the size of the fan?

ATTMA TS1 states that the fan should be able of achieving > 80% of the required air flow rate at 50 Pascals pressure difference. All competent air leakage companies will ensure the aforementioned flow rates are achieved

Information for Material, Plant & Component Suppliers -

Golden Rules to Ensure Part L is Met

Set our clearly in all documentation the level of air tightness that can be achieved and how it is to be practically achieved on site prior to air leakage testing. Be specific about whose responsibility it is to seal components and also adjacent elements, including works on site. Show these details clearly on all contract and site drawings and ensure that specified materials and components are fit for purpose.

Ensure all site staff and operatives fully understand the concepts of air tightness and air leakage testing the details of how it is to be achieved on site. Ensure training is carried out for all the parties involved, including site operatives. All competent air leakage companies should be able to help you through the design process. Air pressure testing has undertaken many design surveys which in turn has helped our clients achieve their  air leakage test pass first time, thus alleviating the need to undertake multiple air leakage tests to achieve Part L compliance  

How can we state air tightness figures for individual components?

Components could be tested in laboratories or tested on site in specially built enclosures as specified in BS EN 12114:2000. The test method allows the air leakage testing through individual joints to be derived. From this information the building air leakage rate can be estimated by totaling up the leakage rates for all the joints in the building envelope.

What can gaps and joints be sealed with?

As with all gaps and joints, there are many BS EN Standards which specify in detail, how they can be bridged effectively. Materials not to use include materials permeable to air (e.g. mineral fibre) or flimsy sheets, thin gaffer tapes or similar are not sufficient materials to seal against Air Leakage. Sealant, expanding foam and tapes can be used, if specified and applied correctly. Ensure that all materials and components are fit for purpose and installed to current standards. All competent air leakage companies frown upon rock wool / gaffer tape etc being used as a air leakage barrier, Air pressure testing can forward a useful pre test checklist if you are unsure of what material should be used in any particular situation.

When To Get Worried

If there is no information on air leakage rates for materials or components, there can be no confidence with the final performance on site. Obtain a component air leakage test – contact Air Pressure Testing Ltd for details.  Many modern construction systems and designs rely on gaskets or sealants within the joint to seal the system.  If these are not installed correctly during installation, the air leakage could be considerable, and subsequently the building may fail the air leakage test. Contact your favourite air leakage company air pressure testing now if you unsure if your sealing is adequate/fit for purpose, it could save you an air leakage failure

A typical example is with block work. Well designed, specified and constructed block work (with full horizontal and perpendicular joints)can achieve a very good standard with air leakage < 2 m3/h/m2.  However, without taking due regard can lead some block work walls to have high leakage rates - for a variety of reasons. Sometimes blocks are not specified with an air leakage rate and also the composition and leakage testing rates of identical blocks, manufactured in different plants, can vary significantly.

On site problems with quality of block work and mortar joints can lead to significant leakage during the air leakage testing. For example, where block work is concealed above suspended ceilings, vertical mortar joints – perps – may not be filled completely but ‘faced up’, which leak, this is where on site audits are at their most effective as they pick up on problems such as this at the construction phase. As air pressure testing’s testing engineers come from senior construction management background, they have a comprehensive knowledge of potential air leakage failure areas unlike many other air leakage companies, that’s why our clients use us again and again   

Information for Building Control Officers & Approved Inspectors

Golden Rules To Ensure Part L is Met

Ensure that the air leakage testing is carried out by a member of BINDT (The British Institute of Non Destructive Testing). The DCLG recognises members as being ‘suitably qualified’ and/or ‘recognised qualifications’ to carry out air leakage tests. All competent air leakage companies should be a member of the BINDT, Air pressure testing is one such air leakage company

What if and how will a building fail the air tightness Part L? 

A building will fail Part L if the air permeability rate is > 10 m³/h/m².  More stringent requirements may be in place, depending on the requirements within the building energy calculation to satisfy the carbon emissions target.

If Buildings also fail Thermographic inspections of the visible envelope, it will show that insulation is not reasonably continuous. As a leading air leakage company air pressure testing can undertake Thermographic inspections to ensure compliance of part L

How accurate are the tests?

ATTMA TS1 states that fan flow rates should be measured to ± 7%.

The accuracy of the air leakage testing itself will be affected by the strength and gustiness of the wind.  The wind will impose both positive and negative pressures on the building envelope, which will vary during the test. ATTMA TS1 states that tests should normally only be carried out when wind speeds are below 6 m/s.  Occasionally a test may have to be carried out in wind speeds above this.  Decisions will be made on a job specific basis. When Wind speed conditions are close to the maximum permitted Air Pressure Testing as a competent  air leakage company will use their Wind damping kits to ensure that accurate readings are undertaken at all times 

How can fire walls be made airtight?

Use the same principles of design and construction as for other air tightness works but use fire rated materials. Compliance to various sections of Part L1 and L2 can be achieved by a ‘competent person’ reviewing the design and/or site works and deeming them adequate. These Sections include air tightness for buildings and continuity of insulation for all buildings. Air Pressure Testing Ltd (as a leading air leakage company) can take on this role and issue the necessary declaration to the Building Control Officer.

Air Pressure Testing Ltd Services has air leakage  testing equipment suitable for testing buildings with floor areas from 10  to 40,000 square metres.  For the easiness of portability Air Pressure Testing Ltd  use their Retrotec 3001 portable high power systems which are 710 mm diameter fans which can be built into sets of up to 3 fans. These are electrically powered, quiet, and clean and as the name suggests portable. They can easily test whole buildings or if necessary be erected inside buildings to undertake air leakage testing on  plenums, service ducts, fire compartments, upper storey’s, extensions, etc, etc.

To undertake air leakage testing on larger buildings Air Pressure Testing can link up to 6 of their Retrotec 3001 3 fan systems this allows us to undertake air leakage testing on buildings upwards of 40,000 Metres, this reduces the need for large trailer fans that can prove to be disruptive to sites with tight access such as city centre’s, when other Air Leakage Testing companies state that they haven’t the equipment to test your building, you know where to come.

Carrying Out Air Leakage Testing & Smoke Tests

Golden Rules to Ensure Part L is Met

Carry out the air leakage testing when the building envelope is complete. Temporarily sealing areas of the building is not only difficult and costly to do well, but the risk of failing increases as well. It is far better to delay the test for a week rather than undertaking the air leakage testing too early, fail, and then have to carry out another air leakage test in one weeks time.

Temporarily seal all heating and ventilation equipment and ensure window trickle ventilators are closed. Check all service ducts (including telephone, electric, spare ducts) and water and condensate traps are either sealed or full.

The worst acceptable standard for the leakage testing rate is < 10 m³/h/m²

Will the building fabric be damaged by pressurising the building to 50 Pascals, during the test?

No. A heavy thunderstorm may impose pressures of 500 Pascals onto the building fabric, so air leakage testing will not cause any structural damage

How long does it take to carry out an air leakage test?

A minimum of 4 hours should be allowed to carry out an air leakage test. It will take approximately 1-2 hours to temporarily seal services, however if the client/customer is proactive and the sealing works are undertaken before we visit site the actual air leakage testing time can be greatly. If the air leakage test runs smoothly, a maximum of 30 minutes is required; but it’s best to allow 1 hour. It takes approximately 1 hour to de-rig all of our air leakage testing equipment. However, if an air leakage testing fails and multiple air leakage tests are carried out or the fan is left running to search for drafts and air leakage paths, then the air leakage testing can run over the usual 2-3 hrs. As one of the leading air leakage companies air pressure testing will always try to undertake the Air leakage test as quickly and efficiently as possible to ensure site disruption is kept to an absolute minimum

Can people carry on working in the in the building when carrying out the air leakage testing?

Yes, as long as no-one opens a door or access hatch which will obviously compromise buildings air barrier – which basically allows the air pressure to drop and the air leakage testing would need to be run again. As one of the competent air leakage companies currently in the marketplace we will ensure site disruption is kept to an absolute minimum

Does the smoke test damage the building?

No. However, the building needs to be empty of all people for Health and Safety reasons due to the poor visibility. It is also essential you inform the Fire Brigade to avoid unnecessary call outs. The smoke is a harmless food grade water based mono-propylene glycol (MPG), but it is a good idea not to expose fresh food or produce to it.

What size fan do we need to carry out the air leakage test?

ATTMA TS1 states that the fan must be capable of achieving at least 80% of the required air volume flow rate, at 50 Pascals pressure difference – Q50. Q50 = A * 10 / 3600 m³/s where 10 is the Air Permeability target, A = Area of walls, roof and ground floor

Note. Air Pressure Testings 3001 series fans can deliver from 1 -  /s to over 70 m³/s so capacity is not a problem

Thermographic test surveys to identify air leakage and/or discontinuous insulation

Air Pressure Testing have many years experience of carrying out Thermographic test surveys and can offer clients advice at an early stage as to the most productive method to carry out a Thermographic test survey.

Air Pressure Testing Ltd offer wide ranging technical and practical construction experience of building technology, design issues and potential faults in buildings allows us to give a high level of service both in carrying out the survey and interpreting the results from the Thermographic test surveys.

Building Thermographic testing thermography is an effective method of indicating the heat distribution over the surface of a building envelope. This remote-sensing technique can be carried out with minimal disturbance by a single operator and allows qualitative detection of air leakage pathways and insulation discontinuities. The Thermographic test survey will be carried out using an un-cooled Thermographic testing thermal imaging camera, which can measure temperatures to 0.1°C and displays the images and reports in full colour. Air Pressure Testing uses a calibrated Thermographic testing FLIR camera, which allows full analysis of saved images. As air pressure testing is a leading air leakage testing company we always ensure that all reports are clear and easy to follow for your future reference

Thermographic test Surveys are carried out to BS EN 13187:1999: Thermal performance of buildings - qualitative detection of thermal irregularities in building envelopes - infra-red method and BRE Report 176 - A Practical Guide to Infra-Red Thermography (Thermographic testing) for Building Surveys.                                                        Please click here to down load a copy

Our On-site Requirements for Thermographic Test Surveys

The following outlines the requirements for the above Thermographic test. Areas of discontinuous insulation will be more readily identified in these conditions:

  • The integrity of the building envelope should be complete for the Thermographic testing survey
  • Drawings (plans and sections) and specification details regarding the areas to be surveyed should be supplied prior to the Thermographic testing survey taking place
  • Air Pressure Testing have assumed that the Thermographic testing survey will be carried out from the outside of the building, usually at night (or on an overcast day in winter) when the weather is dry.
  • It is important that the internal temperature of the building is 10°C higher than the external prior to undertaking the Thermographic test survey
  • If possible, the internal pressure of the building should be raised by 10 Pascals by switching off the extract units prior to the Thermographic test

An hand-held infra-red sensitive Thermographic testing camera records images of the subject that are compared to conventional pictures of the same areas. "Hot-spots" can then be related to features of the building and an informed view taken of building integrity. Local/component thermography whilst a building is depressurised can identify where air tightness needs improving. As one of the leading air leakage companies air pressure testing can undertake both air leakage testing and Thermographic testing to ensure a overall view of your buildings integrity.

Golden rules to ensure Part L is met

You must ensure there is a minimum temperature differential between inside and outside the building of at least 10°C prior to the Thermographic testing taking place. This is usually achieved by leaving the heating system turned on inside the building for 12 – 24 hours prior to the Thermographic test survey.

Carry out external Thermographic testing surveys after dark (or heavy cloud), to ensure problems with sunlight warming up external surfaces can be ignored. Ensure the weather is dry as moist surfaces play havoc with the Thermographic test survey results. Beware items of plant emitting heat inside a building, as they can affect the Thermographic test survey results.

Why use Thermographic cameras?

A thermal image (Thermographic testing) makes it easy to identify areas of missing, misplaced or discontinuous insulation.
It can also be used to identify air leakage paths if used correctly. Cold air leaking into a building will cause cold patches on the surrounding fabric, which can be
identified from thermal images during Thermographic testing. Thermographic testing is a conclusive test to ensure air leakage areas are found quickly and accurately.

Can Thermographic testing surveys quantify air leakage?

No, but they provide a qualitative appreciation of the thermal properties of a building envelope, quickly over large areas and display the Thermographic testing survey  results graphically in colour. Spot temperatures are also measured which can allow for later analysis of the thermal performance of building envelopes, again especially useful in highlighting areas of misplaced or discontinuous insulation, something Air Leakage Testing cannot. Thermographic testing is a conclusive test to ensure air leakage areas are found quickly and accurately.

How can you interpret the thermal/Thermographic test  images?

A sound knowledge of construction technology and a sound knowledge of the projects design (U values, emissivity of materials) allied with experience of on site defects is required to identify the true cause of faults identified on site. Particular care needs to be taken with regard to the emissivity and reflectivity of surfaces. Surfaces with low emissivity (e.g. polished steel), appear colder than their surroundings but are sensitive to reflective heat from background sources e.g. equipment, lights, people etc, can effect the Thermographic test results so special care should be taken during the Thermographic survey

When To Get Worried

If the thermal image of the inside face of a building envelope appears to have a low surface temperature compared to their surroundings during the Thermographic test survey. Take care to evaluate the results as this could be caused by;

·         Missing or damaged insulation or maybe high levels of moisture within the building fabric

·         High levels of air leakage cooling the inside face

·         Thermal bridging

·         Evaporation of moisture from the internal surface

·         Cold rooms inside the building cooling the surroundings

Although Thermographic testing is an accurate way of checking insulation continuation the above bullet points should be carefully followed to ensure the Thermographic results are both accurate and usable for future reference

Typical Procedures for Carrying Out an Air Test

To ensure the air leakage testing is carried out to plan and the risk of failing is minimised, it is necessary for Air Pressure Testing  and the client to work together (as a leading air leakage company APT insures this happens every time). Once Air Pressure Testing receives an order, a procedure is set into train which ensures that everything swings into action. At least a week prior to the air leakage test/s, as a competent Air leakage testing company air pressure testing send clients a checklist of procedures which the client needs to confirm that they are ready for the air leakage test. Please find attached checklist

The e-mail/fax back includes the following points;

1. Air leakage test time and date must be established. Note, the client can change the date of the air leakage test up to 72 hours prior to the test without charge. Air Pressure Testing must be informed at least 5 days prior to the air test of any major temporary works, as these may adversely affect the result of the air leakage test. As a proactive air leakage testing company we will always listen if a last minute problem has occurred and therefore effects your air leakage test date

2. Access to the door where the fan is to be set up, should be flat and accessible.

3. Air Pressure Testing set up the screen for the fan if it is a double door. The client must build a screen if the door to be used is a loading bay door.

4. Air Pressure Testing assume that the building envelope is complete and ready for the air leakage test. It has been assumed that the works will take 5 hours to complete. 99% of air leakage tests are completed within 5 hours. As one of the leading air leakage companies we will always try to finish the Air leakage test in a quick and efficient manner

5. Air Pressure Testing request that the architect calculates the envelope area figures as it is not always evident from drawings where the envelope of the building lies. The air tightness envelope of the building
follows the insulation in the floor slab, external wall and roof. Plant rooms ventilated to outside
and cold roofs therefore should generally be excluded from the envelope area figures. Note, Air Pressure Testing verify these figures from drawings supplied or on site. The envelope area is required before the air leakage testing date, in order to give a result on the day. As one of the leading Air leakage testing companies air pressure testing will always check the architects calculations prior to the test .

6. The check list details what temporary sealing needs to be carried out, prior to the air leakage test. As a competent air leakage company we will always ensure you receive the relevant checklists prior to the Air leakage test.

7.To summarise temporary sealing is not required on loading bay; external doors/frames/thresholds; windows and cills; lift shaft vents and doors; electrical switch, plant, tank rooms; smoke exhaust fans and vents.

8. Temporary sealing is required on fresh air inlets and exhausts to air handling plant temporarily
sealed. Check that drains, water traps are all filled with water.

9. Attendance from the specialist H & V sub contractors is required to shut off and close down all H and V equipment and any other equipment that form openings or penetrations in the envelope and temporarily seal them. Air Pressure Testing accepts no responsibility for these works, although Air Pressure Testing Ltd check the sealing is adequate. Note service ducts (gas telephone etc) need to be sealed as well.

10. The Client must inform all contractors and personnel that access into and out of the building will be restricted for a period of at least 2 hours and ensure that this is observed. Note, works can still proceed on site as usually access is restricted for periods of 30 minutes at any one time during the air leakage test.

11. All internal doors, air sealed plenums / suspended ceilings / raised floor systems are effectively fixed opened to enable unrestricted air flow into all parts of the building envelope.

On the day of the Air Leakage Testing Air Pressure Testing usually turn up early morning and go through site induction procedures.

1. Prior to setting up their own air test rig, Air Pressure Testing walk the site with the clients’ engineer and ensure everything is set up correctly. Once agreed that everything is set up, the air leakage testing can proceed.
Hopefully, the first air leakage test is successful and passes the specification criteria.

2. If the first air leakage test fails, Air Pressure Testing again walk the site and identify why it has failed. If this can be put right, remedial works may be applied by the contractor and a second air leakage test carried out, air pressure testing will walk around the building prior to the air leakage test and will report any area/s that need to be sealed


3. Further air leakage tests are then carried out and if the air leakage test still fails, Air Pressure Testing can look for leakage paths by using portable smoke generators or pencils to identify where air is leaking. Another method usefully employed is to set the air leakage testing rig in reverse, thereby de-pressurising the building and feeling for drafts on the inside face of internal walls. Either way, Air Pressure Testing technicians use their experience of being one of the most proactive air leakage companies to help with the air sealing this in turn helps the contractor. It usually becomes obvious whether or not the air leakage test result will be brought under 10m³.h-1.m-² within the day.

4. Prior to leaving site, the air leakage test result is discussed with the clients’ engineer.

Establishing the Size of Air leakage Testing fan Required for the Size of Building to Be Tested

This is relatively simple, as the size of the fan determines how much air the fan can blow into the building in per second. The air blown in, equals the air leaking out and linking this to the requirements of Part L2 enables Air pressure Testing to determine what size fan system is required, as one f the leading air leakage companies air Pressure testing will always provide a machine with the capacity to correctly undertake the air leakage test

Examples of air leakage testing rigs for different size buildings.
Building of 1000 m² floor area, assume 2 storey’s, 20*25m on plan and average 10 m wall height.
Envelope area = Area of ground floor = 500
+ Area of roof = 500
+ Area of walls = 900
Envelope area = 1,900 m²

Assuming the building is just complying with Part L2 and is leaking at 10 m³.hour-1.m-² at 50 Pascals. The total volume of air leaking out of the building = 1,900 * 10 = 19,000 m³.hour-1
= 5.3 m³.second-1

ATTMA TS1 states that the air leakage testing rig should provide a minimum of 80% of the volume flow rate.
The air leakage testing rig must have a volume flow rate up to 80% of 5.3 m³.second-1, 4.24 m³.second-11

 

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