Air exchange

The most energy efficient homes are almost airtight to avoid heat loss. As a result, very little energy is needed to heat them.

The gold standard in energy efficient homes is the Passivhaus. Passivhaus is German for “passive house”, so called because in a lot of cases it doesn’t need to be actively heated at all. 

Whilst it might not be possible to retrofit a house to Passivhaus standards, some of the same principles apply to improving your property’s energy efficiency. Adding more insulation to our homes makes our home more airtight.

The big benefit of this is that less warm air can escape, so our homes stay warmer.

The downside is that fresh air has a harder time getting into our homes. Since air flow is important for keeping our homes healthy, we have to find a way to exchange stale, moisture-heavy air, for fresh air.  

A Passivhaus allows air exchange through a ventilation system known as Mechanical Ventilation Heat Recovery (MVHR). If you’re able to achieve a high level of insulation in your property, MVHR might be necessary to ensure healthy air exchange. 

Mechanical Ventilation with Heat Recovery (MVHR) 

A Mechanical Ventilation with Heat Recovery system: 

• Extracts warm, stale air from the rooms in your home 
• Blows in fresh air 

The “Heat Recovery” part of MVHR refers to how the system reuses the warmth from the outgoing stale air. MVHR extracts the warmth from the air it’s blowing out and uses it to preheat the incoming fresh air. It’s basically a form of recycling. The heat produced by activities like cooking or showering is captured and used to warm the rest of your home.   

Other types of air exchange 

Unless your home is extremely well insulated, it’s unlikely you’ll need a MVHR system. However, it’s still important to allow air exchange. Check out our Ventilation guide for other ways to keep your home fresh and healthy.