If you insulate, you must ventilate
Ventilation losses can represent around 40% of the energy losses in a north east home.
If you insulate a building, or improve it's airtightness, you might be trapping more warm-moist air in the building. If this moisture builds up it could lead to surface condensation or mould.
Worse still, if warm moist air escapes into the building fabric it could cause interstitial condensation and unseen damage to the building.
We must replace uncontrolled ventilation with well-designed ventilation systems, preferably ones that recover heat in the process.
Existing Ventilation in dwellings
Existing buildings, particularly older buildings, have lots of uncontrolled ventilation.
Common leak points include:
> Poorly installed windows
> Poorly fitted loft hatches
> Floor Hatches
> Poorly fitted extractor fans
> Failed door and window seals
> Open fireplaces or open log-burners
There are two types of energy losses associated with these leaks:
Infiltration - On a windy day warm air is blown out of the building as cold air is blown in
Buoyancy - Even on a still day, warm air rises up and out of the building as cold air is drawn in though the bottom
The best way of finding leaks in the building fabric and measuring the airtightness of the building is with a test.
An Air Permeability Test, also known as a Blower Door Test, takes several hours to conduct and costs around £400.
A large fan is fitted to the front door of the home and a computer measures the pressure loss as the fan blows and sucks on the house.
Improving Air Permeability
The good news is that air-tightness is one of the cheapest ways of reducing energy consumption.
Special air-tight tapes and sealants can be used to seal around windows, skirting boards, and other problem areas.
If you'd like more advice on the right products to use and how to apply them, please get in touch
Installing a proper ventilation system will ensure better indoor air quality, less moisture and the elimination of condensation damp and mould.
There are lots of systems out there, these are two of the most suitable systems for homes in the North East.
dMEV - decentralised Mechanical Extract Ventilation
Continuous extractor fans are installed in bathrooms, kitchens and other wet-rooms. These extractor fans run 24 hours a day and may have different speeds of operation and sensors that monitor moisture and CO2 levels. They react to the internal air conditions by changing speed when moisture or CO2 levels rise.
This system requires background ventilators, such as trickle vents, in bedrooms, living rooms and other reception rooms. Fresh air enters these rooms and makes it way through the house.
For this reason doors must allow air to pass, even when closed, usually by having a 10mm gap underneath them.
Mechanical Ventilation with Heat Recovery - MVHR
Ducts are required to every room that connect back to a central unit.
Moist stale air from kitchens, bathrooms and wet-rooms is extracted through the central unit, via a heat exchanger, to the outside.
90% of the heat is recovered from the outgoing air and transferred into fresh air that is pumped into all the reception rooms.
Installing the duct work can be difficult, but the room-in-roof spaces and loft spaces can be surprisingly well suited to this.
The systems are almost silent and run 24 hours
The home can be made airtight, thereby improving the energy efficiency without affect the quality of the indoor air.
Homes with MVHR have less CO2 and less pollutants in the air you breath making them incredibly good for your health.
If you have any questions about these systems and would like an appraisal please get in touch