Airtightness- the control of air leakage in a building i.e., the elimination of unwanted draughts through the external fabric envelope. This can be achieved by Retrofit. There are various private and govt funded retrofit schemes available. The main one is the whole house’ or ‘whole building’ retrofit which is derived from PAS2030/PAS2035 This is an approach to the installation of energy efficiency measures (EEMs) that considers the requirement of the entire building, both from a technical standpoint and considering factors like occupancy comfort.
The benefits of a whole house are domestic retrofit and Airtight buildings:
- Energy Savings
- Greater Building Durability
- Higher Resale Value
- Indoor Environmental Quality
- Improved Comfort
A more efficient home that will be warmer, cheaper to run, and less draughty. An energy-efficient home will save you money over its lifetime. A better Energy Performance Certificate (EPC) rating is likely to increase the value of your property.
Examples of retrofitting include:
- Insulating roofs, walls, and floors
- Replacing windows with double, triple-glazed, and energy-efficient materials.
- Improving ventilation or draught proofing
- Installing efficient heating and hot water systems
- Installing renewable energy e.g., solar panels
With buildings becoming more airtight is a risk in waiting. A risk of moisture and condensation which may lead to mold. As good as the air tightening is the building would also need to be well-ventilated, to allow moisture and air management the reason for Air permeability testing and Ventilation system installation. Air permeability is the measuring of the air tightness of a building fabric, defined as the Air leakage Rate per Hour per Square meter of the envelope area. (Air Change Rate ACR/Hour/m2)
Airtightness is about reducing the unintentional introduction of outdoor air into a building or limiting the loss of air to the outside.
In the UK the approved procedure for air pressure testing of dwellings is CIBSE TM23 which is based on BS EN 13829:2001 9 (Building standard) and ISO 9972:2015.
It is a requirement of Approved Document L that any dwelling tested must achieve an air pressure test result (or air permeability) of less than or equal to 8m3/h/m2 at a pressure differential of 50 pascals with the Blower door a high-pressure testing method or 1.57m3/h/m2 at a pressure differential of 4 pascals with the Pulse a low-pressure testing method.
PAS recognises this co-dependency.
- If the post-retrofit Q50 is better than 5 m3/hr/m2 then continuous running ventilation (such as MVHR or MEV) is recommended.
- If post-retrofit Q50 is worse (i.e., leakier) than 5 m3/hr/m2, trickle vents with intermittent or passive ventilation are permitted.