I am Graham, I have been air testing buildings for over 10 years, I enjoy working with site teams from large commercial schemes to air tight Passivhaus. Working together we have achieved some great results along the way.
Many property owners get their dwellings tested for air tightness to reduce their environmental impact, save money on energy bills and decrease energy waste. As air tightness testing is now a part of the Building Regulations, all new builds (both domestic and non-domestic) must adhere to air tightness standards; that’s why it’s so important for us to understand about the many layers of air testing.
Air tightness testing is the practice of measuring the amount of air that escapes through the gaps or building fabrics of dwellings. Blower door testing equipment is installed to pressurise the building and test pressure differences which helps to see areas need fixing.
So, the big question is how do you get a good air tightness test result on your property? Maximizing your chances of achieving a good air tightness test result starts in the planning and preparation, as well as a good overall understanding of requirements from the property owner. To help get you up to speed, we will be going back to basics in this blog to really give you an in-depth insight into air testing.
In April 2002, the UK government introduced air tightness testing alongside the Building Regulations law to enforce standards of dwelling air tightness. The legislation was created in order to lower running costs, verify the standards of materials, prevent uncomfortable drafts and avoid condensation problems.
The air tightness test determines the amount of air leakage in cubic metres per square metre of internal surface area of the building m3. Or, to put it simply, air tightness testing measures the amount of air that escapes through the gaps or building fabrics. Ideally, having an airtight building means that less energy will be wasted through the leakage of heated air.
Air tightness testing is required for all new builds both domestic and non-domestic, in addition to the requirements detailed in Part L of building regulations sections 1A and 1B. Once tested (and the build’s air tightness quality improves) it will lower the environmental impact of the building as well as saving the owner money on energy bills. Where do we sign up?!
To complete an air tightness test, access to an empty dwelling is required. Air testers install blower door testing equipment – essentially big fans – to an external opening like a doorway. They will then use this to pressurise the building and test over pressure differences. The external air pressure then flows in through the cracks and openings.
The fan will typically depressurise the house to a pressure of at least -60Pa. An anemometer will read the internal pressure, external pressure and the strength that the fan has to work at to create the pressure difference. This will help to calculate the air leakage.
With so many building regulations to consider, it can be confusing to know which ones apply to you. Since 2006, all new developments in the UK are required to have an air test carried out as part of the approved document Part L.
Residential properties that go over 500 m2 must undergo air tightness testing to comply with the Building Regulations/Standards to meet target emission rates. In addition, small developments of one or two properties must have one of the buildings undergo testing. Larger developments are required to have a bigger proportion of buildings tested, depending on the size and construction of the dwellings. There are some exceptions to this, but if you are still unsure whether your building needs to be tested, we would be happy to speak to you.
Again, there are also many factors that influence the price, such as how many dwellings require a test and how many locations these dwellings are positioned.
Here at Buildpass, our air tightness test service starts at £110. It’s worth noting that a good deal of studies have suggested that a dwelling with an exceptional air tightness score has the potential to be sold at a far higher price due to the reduction in energy consumption and costs over the lifetime of the dwelling.
How long does an air tightness test take?
The duration of the air tightness test will depend on many factors such as the size of the building and the level of air leakage. On average, a test should take under two hours and you should receive a test score, if you are successful, either the same or following day. For Passivhaus tests, we are required to undertake both a pressurisation and depressurisation test, which can take slightly longer.
Before testing, passive ventilation in the building is temporarily sealed. The exterior envelope and all its openings are also closed. Internally, all doors are temporarily fixed open. Air testers install blower door testing equipment to an external opening which will pressurize the building and test over pressure difference. The external air pressure then flows in through cracks and openings, helping us to identify the areas that need fixing in the building.
Before you have an air test performed, it’s essential for your dwelling to be complete. It might seem like a lot, but this does include walls, windows, skirting, lighting, switches and doors. You will also need your SAP score as this will set a target for the air test.
Although you need to wait to have your air test undertaken, you can employ the support of an energy advisor from the word ‘go’ to make sure your designs have been created with air tightness in mind to save you time and energy in the long run!
If you are targeting an extremely efficient building, we recommend you undertake at least two air tests. One when the shell of the building is complete and one at the end of the project to ensure that the building is performing as targeted and, if not, remedied prior to fit out works starting.
For more information, check out our previous blog.
Current building regulations say that new dwellings should achieve an air leakage of around 10m3/hm3 or less. This is the air leakage per hour, per square metre of envelope/fabric area. However, the building that is used as a benchmark building regulation uses a target of 5m2/hrm2. With this in mind, we recommend you target at least 5 or below to ensure the building complies with both carbon emission and fabric energy efficiency targets.
Overall, your air tightness target can be influenced by a number of factors. For an in-depth analysis of your target based on building and ventilation type, you can download our FREE guide – 12 steps to air tightness or read our blog on our top 10 tips for improving your air test score.
If we have convinced you to get your property air tightness tested, we can help! Our team can help with the planning and design of your property in addition to carrying out the air test. Get in touch with our team today to book a consultation and get your air test booked in for the near future.
The concept of pressure comes into play when we talk about force area and the application of this force perpendicularly to a particular surface area. Have you ever thought about why the nails we use are manufactured with sharp ends or why the knives need to be so sharp?
The answer to all these questions is pressure force, which is defined as the force per unit area or the ratio of the force applied to the surface area over which the force is applied.
Hence, we can define pressure as:
The force applied per unit area, perpendicular to the surface of an object over which that force is dispersed or distributed is known as pressure.
When a force of ‘F’ in Newton is perpendicularly applied to a surface area ‘A’, the pressure exerted on the surface by force is equal to F to A. Therefore, the formula for pressure (P) is:
P = F / A
Pascal (Pa), th SI unit of pressure.
The force of one newton applied over a surface area of a one-metre square is known as 1 pascal.
1) What happens to the pressure, when the area decreases?
a) Pressure decreases
b) Pressure increases
c) No change in pressure
d) Pressure remains constant
Correct Option: (b)
Explanation: Since, Pressure (P) = Force (F)/Area (A)
Hence, we can conclude from the above equation that pressure is inversely proportional to area. So, if the area decreases, the pressure increases.
2) The decrease in pressure takes place when _____>
a) The force is increased but not the area
b) The area is decreased but not the force
c) Either force increases or area decreases
d) The area increases and the force decreases
Correct Option: (d)
Explanation: Since, Pressure (P) = Force (F)/Area (A)
Therefore, we can conclude from the above equation that the pressure is directly proportional to the applied force and inversely proportional to the area.
Hence, if the area is increased and/or force is decreased, the pressure will decrease.
3) What will be the relation between F and F’ if a force F is acted upon a uniform rod of cross-section A and a force F’ is acted upon a uniform rod of cross-section 4A, and the pressure on both the rods is the same?
a) F/F’ = 1/4
b) F/F’ = 4
c) F’/F = 1/4
d) F/F’ = 1/16
Correct Option: (a)
Explanation: Pressure (P) = F/A (on first rod)
Pressure (P’) = F’/4A (on second rod)
Given;
P = P’
F/A = F’/4A
F/F’ = 1/4.
4) Find the ratio of pressure on the first cube (P) to the pressure on the second cube (P’). If some force is applied on the first cube of side 4m, and another force is applied on a cube of 2m, and the magnitude of this force is double than that of the previous force.
a) 1/10
b) 1/8
c) 1/20
d) 1/12
Correct Option: (b)
Explanation: P = F/42
P = F/16
P’ = 2F/22
P’ = F/2
P/P’ = (F/16)/(F/2)
= 1/8.
5) Pascal’s Law is valid only for _____.
a) Metals
b) Water
c) Solids
d) Fluids
Correct Option: (d)
Explanation: For water, gases and even other liquids, Pascal’s Law is valid. But, for any other form of matter, it is not applicable. Hence, Pascal’s Law is valid only for fluids; this can be concluded from the earlier fact.
6) Which among the following statements is stated in Pascal’s Law?
a) For every action, there exists an equal and opposite reaction.
b) The pressure for an ideal gas having constant volume and mass is directly proportional to temperature.
c) A change in pressure at any point in the fluid is transmitted so that the same change occurs everywhere throughout the fluid.
d) None of these.
Correct Option: (c)
Explanation: Pascal’s Law says that – A change in pressure at any point in the fluid is transmitted so that the same change occurs everywhere throughout the fluid.
7) The working of hydraulic machines is based on which of the following laws?
a) Ideal gas law
b) Newton’s law of cooling
c) Universal law of gravitation
d) Pascal’s law
Correct Option: (d)
Explanation: Pascal’s Law says that – A change in pressure at any point in the fluid is transmitted in such a way that the same change occurs everywhere throughout the fluid. This phenomenon is widely used in hydraulic machines by changing cross-sectional areas at required places.
8) What is the SI unit of pressure?
a) Kelvin
b) Candela
c) Pascal
d) Joule
Correct Option: (c)
Explanation: “Pascal” denoted by “Pa” is the SI unit of pressure, which is named after the famous scientist Blaise Pascal.
1 Pa = 1 N/m2
9) Name the instrument that is used to measure pressure.
a) Voltmeter
b) Odometer
c) Barometer
d) Ammeter
Correct Option: (c)
Explanation: To measure air pressure, a scientific instrument named “barometer” is used. Since pressure varies with altitude, a barometer can also be used to measure the altitude of a region.
10) A nail is always manufactured with one end pointed to confirm that for a given amount of force applied to it. True or False?
a) True
b) False
Correct Option: (a)
Explanation: The force per unit area is known as pressure. And to drive the nail easily into the wall, we need more pressure. So, a nail must be manufactured with one end pointed so that the pressure applied on it could be more.
1) Define pressure.
2) Define 1 pascal.
3) What are the different types of pressure?
4) What are the factors that affect pressure?
5) What is absolute pressure?
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