Air Sealing & Fire Stopping Information for the Building Services Consultants

Air Seaing Information Pack PDF download

Advice & Quotation

Air Sealing Brochure (PDF)

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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. Natural ventilation openings should be fully controllable and therefore offer a reasonable standard of air tightness in the closed position. Check the envelope area is correct.

Frequently Asked Questions

What British Standards are air leakage pressure tests carried out to?

ATTMA TS1 Measuring Air Permeability of Building Envelopes
BS EN 13829:2001 Thermal Performance of Buildings: Determination of air permeabil-ity of buildings – Fan pressurisation method.

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

For a moderately sized single storey building which complies with Part L, Qleakage = <10m³/(h.m²), the average ventilation rate will be approximately 0.2ach. 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 m³and 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 5000m², currently built without air tightness considerations, air permeability can be >14m³/(h.m²). This equates to a hole in the roof of approximately 5m²!

If the air permeability can be reduced to 8m3/(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 2m³/(h.m²).

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.

How can plenums be air sealed?

For plenums to be effective, they need to be reasonably air tight. HRS have air sealed and tested a variety of plenums and can offer advice for any particular project.