What is Building Air Tightness?

Building Air Tightness is the ‘air permeability’ or air leakage rate through the Structure. It is used to measure and quantify uncontrolled flow of air through the building structures envelope’s cracks, gaps and cavities, sometimes referred to as air infiltration or drafts, created by structural damage, poor workmanship, weather, design or deterioration of materials.

This is uncontrolled air movement can result in drafts, moisture ingress and energy losses. This is not to be confused with ventilation which is the controlled flow of air in and out of a building which provides fresh air and removes unwanted moisture, odours and pollutants.

The aim should be to ‘BUILD TIGHT – VENTILATE RIGHT'.

Why is Building Air Tightness important?

It is important to reduce Air leakage from a building to reduce cold drafts entering and hot air escaping, which reduces energy to maintain comfort levels or to simply improve the level of comfort. Elimination of drafts also means occupants can reduce heating by a few degrees and still maintain comfort levels
The dramatic rise in the cost of oil, gas and electricity means that the only sure way to reduce heating costs is by reducing the amount of Energy used in the first instance. Reducing air leakage from the building envelope is better than increasing fuel usage to maintain a comfortable environment and more cost effective than upgrading heating systems and building insulation.

Building regulations have driven down fabric heat losses in the last few years and there is limited return increasing insulation to reduce them further. Sealing air leaks is one of the simplest and least expensive ways to save energy.

• Staff productivity-better work environment
• Heating systems often 50% oversized
• Up to 40% higher Energy consumption due to air leakage. (15-30%improvement)
  

How Do We Air Tightness Test?

Air tightness is measured using a Air door Blower unit which consists of a variable speed computer controlled calibrated fan contained in a tightly sealed adjustable frame with air tight nylon panels that is temporarily mounted in an external door jamb External windows and doors are closed. and All ventilation systems eg chimney openings, extract fans and for the generation of the test.vents are sealed.

The door blower fan is switched on and the air flow through is increased until a pressure of 50- 60 Pa(recreates the same effect as 20 MPH Winds blowing outside ) is achieved. The total air flow through the fan and the building pressure differential (inside to outside) are recorded. The fan speed is then slowly reduced in steps down to around 20Pa with the fan flow and differential data recorded at each step.This is then divided by the total building envelope area to calculate the number of air changes per hour.

From July 1st 2008 mandatory airtightness testing of new Dwellings need to meet a minimum level of air permeability (Q50 < 10m3/h/m2). This means that a pressure difference of 50Pa on the external envelope of the building 10m3 of air per hour passes through every square meter of the external envelope Testing is performed to the European Standard EN13829.

What is Building Thermal Imaging?

Building Thermal Imaging is the use of an infrared imaging and measurement camera to "see" and provide precise non-contact temperature measurement of thermal energy emitted from an object. Thermal, or infrared energy, is light that is not visible because its wavelength is too long to be detected by the human eye; it's the part of the electromagnetic spectrum that we perceive as heat The higher the object's temperature, the greater the IR radiation emitted. Infrared allows us to see what our eyes cannot Building thermal imaging uses an infrared camera to see heat loss through the structural envelope, quantify it with precise non-contact temperature measurement, and document it in a professional IR report.

Why is Thermal Imaging used in Air Tightness?

‘A picture says a thousand words’ A Thermal Imagine is the only diagnostic technology that lets you instantly visualize and verify thermal performance
Gaps and cracks in the building fabric are often difficult to detect simply by hand or by visual inspection. Air leakage paths through the building fabric can be tortuous. Gaps are often obscured by internal building finishes or external cladding. The only Satisfactory way to show that the building fabric is reasonably airtight is to measure the leakiness of the building using thermal imaging and air tightness testing as a whole.Once located draughts can often be simple and inexpensive to seal 10 to 30% Savings

Is Building Air Tightness Testing Mandatory?

Mandatory Air pressure testing from 1st July 2008 required by Irish building regulations. The revised Irish Building Regulations (24th January 2008) introduces mandatory air pressure testing for new dwellings planning applications from 1st July 2008.

Transitional arrangements
Dwelling planning applications before 1st of June 2008 are except must have the structures of internal walls erected by1 July 2009 All new single dwellings require an air pressure testing from 1st July 2008.