6. Draughts

Revisions to the building regulations in 2021 (implemented in June 2022) recognise the increasing interaction between energy, the conservation of fuel and ventilation (Approved Documents Part L and Part F). To save energy in a modern home we are encouraged to decrease the heat losses through uncontrolled ventilation, through gaps and openings in the construction, but we also have to ensure that there is enough fresh air coming in to support healthy living. These changes are based on research and a better understanding of how ventilation is used in homes. The effective area for background ventilators has increased but when the new standards are applied will it be comfortable to sit near or below a traditional window ventilator? (See infographic to left.)

Homes will require adequate background ventilation but when this is supplied directly from the outside will there be an uncomfortable downdraught? The first instinct may be to close the ventilator or block it off with probable consequences for air quality. We know this has been happening in reality, even in homes with the low background ventilation required by the 2010 regulations. 

Low energy strategies such as Passivhaus ensure that fresh air can enter a home consistently and comfortably by pre-warming the incoming air in a heat exchanger. In fact, the standard, which is a comfort standard as well as an energy standard, cannot be met without mechanical ventilation and heat recovery (MVHR). Have we reached a point where all homes should have mechanical systems to ensure that there is adequate background ventilation with pre-warmed incoming air? 

Things that can go wrong:

• Noticeable draughts and uncomfortable interiors;
• Poor air-quality if ventilation is blocked or deliberately limited;
• Additional load for the heating system to counter displacement of warm air with cold outside air.

Future-proofing recommendations:

• DESIGN: Education and knowledge-building for ventilation in very low energy homes;
• DESIGN: Design for comfort as well as energy and carbon saving;
• DESIGN: Monitoring of homes built to new standards will be essential to understand the effectiveness of the changes in 2022 and to inform the Future Homes Standard.