Air Tightness testing – the
resistance of the building envelope to inward or outward air leakage. Excessive
air leakage results in increased energy consumption and a drafty cold building.
Air tightness 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 tightness testing companies currently practicing under 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 tightness testing companies we can quickly and accurately explain what category your building fall in to
The reason the
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 tightness testing and
continuity of insulation, APT can quickly help your company achieve the
required results as one of the leading air tightness 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 tightness 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.
Air Tightness 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 tightness test by
reputable air tightness 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 tightness 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.
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 suffering 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 tightness
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 tightness 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 tightness 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 tightness rate using our proactive
approach as one of the leading air tightness companies
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 tightness companies
The air permeability of the
envelope should be no greater than 10m³/h/m² during the air tightness test.
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 Air
Pressure Testing if you are unsure, we can help you identify your required air tightness/leakage
rate using our proactive approach as one of the leading air tightness 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 / tightness standards have been achieved by passing the air
tightness test, systems have been commissioned and operating instructions issued.
As a leading air tightness company Air Pressure Testing provide a fully
compliant air tightness report
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 Air Pressure Testing the most proactive air
tightness 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 tightness testing companies
Air tightness 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.
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 tightness 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 tightness 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
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 tightness company.
Has the envelope area been independently verified -
by the architect? Check that the air tightness test has been carried out on the
same envelope criteria – i.e. no areas have been excluded for the air tightness
test and included in the calculations, if so this must be clarified to the air tightness
company
2.
Check the envelope area calculations refer to the whole
building envelope and that this is the envelope that has been actually air tightness
tested by the air tightness company
has the envelope area been independently verified - by the architect?
3.
Check that the air tightness test has been carried out on
the same envelope criteria – i.e. no areas have been excluded for the air tightness
test and included in the calculations.
4.
The whole building should be air tightness 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 tightness company undertaking
the Air tightness 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 tightness test. Contact the
air tightness company if you are unsure what vents etc require sealing
6.
During the air tightness 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, these levels should be achieved during the air
tightness test.
·
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 Air Pressure Testing (the most proactive air tightness company) if
you are unsure of your air tightness requirements
Commercial
Benefits to the Building Owner and Client by working with Air tightness 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 tightness 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 tightness / 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 tightness 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 tightness
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 tightness 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 Air PressureTesting if you unsure of your air tightness specification
What is the
Good Practice Guidelines for
Good
Practice Guidelines for
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 |
Theory of
Air Tightness, Air tightness Testing and Air Sealing Measures
Air tightness / air permeability
(air tightness testing) – defined as the resistance of the building envelope to
inward or outward air permeation. Air tightness driven is 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 air tightness testing can alleviate this by
finding the air leakage paths within the building fabric. For the client, air tightness
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 tightness 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 parties along
with your practicing air tightness 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. Throughout the air tightness
test 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 tightness
company should always try to achieve this air flow during the air leakage test
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 tightness company now if you are unsure
or need extra info
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 tightness company should help you through the air tightness
process
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 a party claims that air
leakage problems will be sorted out after the first air tightness 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 tightness 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 tightness company should be able to undertake a
survey prior to the first air tightness test to ensure the chance of air tightness
failure is kept to an absolute minimum
Designing airtight buildings is the
only means of ensuring long term, low air tightness testing 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. Ask
Air Pressure Testing to undertake a air tightness survey if you are unsure of
your buildings envelope integrity prior to the air tightness test
Ensure that the air tightness 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 tightness testing.
Air Pressure Testing is one such air tightness / air leakage
company
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 favoured air tightness company Air PressureTesting
now for up to date air tightness advice
Where can I access reference to standard details?
·
The
Stationery Office –
·
Kingspan
·
SEDA
·
The
Stationery Office
·
MCRMA
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 this is a common reason for Air tightness
failures
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 tightness test. Many air tightness
companies can offer this air tightness testing sampling service
Ensure that good, sound building
practice is delivered so that the building is airtight and therefore doesn’t
fail the air tightness 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 during the air tightness test, 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. Air
pressure testing found the areas that leaked and organised the air tightness
sealing works. Just one of the reasons Air pressure testing is one of the
leading air tightness testing companies for highlighting 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 tightness testing failure will
be greatly increase. As above Air pressure testing is one of the leading air tightness
companies for highlighting your air leakage areas
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 tightness test fails,
how can air leakage paths be found? As a leading air tightness company Air
Pressure Testing uses a variety of techniques that can be used to identify
leakage paths – these include;
·
Feeling
for drafts adjacent to the air barrier, whilst the building is being air tightness
tested. It is useful if the air tightness 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 tightness 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
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. Air pressure testing can identify all potential air leakage
areas to ensure you pass your air tightness testing first time!
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 tightness company can help
clarify these hard to find areas of air leakage during the air tightness
testing.
|
Envelope |
Leakage Rates (m3/hr
at 50Pa) |
|||||
|
|
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) |
||||||
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 an air tightness test if gaffer tapes etc
is being used as a long term barrier against air leakage.
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 tightness testing.
Check the envelope area is correct. All competent air tightness companies will
undertake the checking of the building envelope as it is critical the size is
correct otherwise it will affect the overall result and could end in a air tightness testing 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 tightness companies will undertake the air tightness testing to the above
specification.
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.
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.
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 tightness testing where the results have been below 1 m3/h/m2
so these figures for air tightness are easily achievable.
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 tightness company air
pressure testing can undertake the sealing of all penetrations prior to the air
tightness test.
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 tightness companies will ensure
the aforementioned flow rates are achieved
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 tightness 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 tightness 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 tightness test pass first time, thus
alleviating the need to undertake multiple air tightness tests to achieve Part
L compliance
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 tightness 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.
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 during the air tightness test. 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 tightness
companies frown upon rock wool / gaffer tape etc being used as an 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 so you can be suitably prepared prior to the air tightness test.
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 tightness test. Contact your favourite air tightness company
air pressure testing now if you unsure if you’re sealing is adequate/fit for
purpose, it could save you an air tightness 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 air tightness < 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 tightness
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 air tightness
surveys / 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 tightness failure areas unlike many other air
tightness companies, that’s why our clients use us again and again as we
understand how
buildings are constructed
Ensure that the air tightness testing
is carried out by a member of BINDT (The British
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 tightness company air pressure
testing can undertake Thermographic inspections to ensure compliance of part L
ATTMA TS1 states that fan flow
rates should be measured to ± 7%.
The accuracy of the air tightness 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 an air
tightness 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
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, this reduces site disruption during
the air tightness test. They can easily test whole buildings or if necessary be
erected inside buildings to undertake air tightness testing on plenums, service ducts, fire compartments,
upper storey’s, extensions, etc, etc.
To
undertake air tightness 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 tightness 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 Tightness Testing companies state that they
haven’t the equipment to test your building, you know where to come.
Carry out the air tightness 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 tightness testing too early, fail, and then have to carry out another air
tightness test in one week’s 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 in
all cases you must get below this during the air tightness test to achieve a
pass!
No. A heavy thunderstorm may impose
pressures of 500 Pascals onto the building fabric, so air tightness testing
will not cause any structural damage
A minimum of 4 hours should be
allowed to carry out an air tightness 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
tightness testing time can be greatly. If the air tightness 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 tightness testing equipment.
However, if an air tightness testing fails and multiple air tightness tests are
carried out or the fan is left running to search for drafts and air leakage
paths, then the air tightness testing can run over the usual 2-3 hrs. As one of
the leading air tightness companies air pressure testing will always try to
undertake the Air tightness test as quickly and efficiently as possible to
ensure site disruption is kept to an absolute minimum. Air pressure testing can
also undertake the air tightness test out of hours to further minimize site disrupton
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 tightness testing would
need to be run again. As one of the competent air tightness companies currently
in the marketplace we will ensure site disruption is kept to an absolute
minimum
Does the smoke test damage the
building during the air tightness testing?
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 during the air tightness smoke 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 Testing’s 3001 series fans can deliver from 1 - m³/s to over 70 m³/s so capacity is
not a problem
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
tightness 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
The following outlines the
requirements for the above Thermographic test. Areas of discontinuous
insulation will be more readily identified in these conditions: