By building homes that have excellent thermal performance, exceptional airtightness and mechanical ventilation, Passivhaus (or Passive House) homes developed by the Passivhaus Institute can cost under £100 a year to heat. Here, we take a look at how houses are completed to the Passivhaus standard, how they save money on heating bills, and how energy efficient homes are great for landlords and tenants alike.
What is Passivhaus?
Passivhaus buildings see a 75% reduction in their space heating requirements in comparison to a standard UK new build home, making them much cheaper to heat.
Dr. Wolfgang Feist, the Director of the Passivhaus Institute says that:
“The heat losses of the building are reduced so much that it hardly needs any heating at all. Passive heat sources like the sun, human occupants, household appliances and the heat from the extract air cover a large part of the heating demand.
The remaining heat can be provided by the supply air if the maximum heating load is less than 10W per square metre of living space. If such supply-air heating suffices as the only heat source, we call the building a Passive House.”
The Passive House standard
Passive House buildings are designed to help the industry meet the 80% carbon reductions set as a target by the UK Government.
To meet the Passive House standard, traditional heating systems must no longer be essential, and at night, the use of natural cross-ventilation through open windows is encouraged, particularly in summer.
In meeting the Passive House standard, homes also have excellent indoor air quality. This is because air infiltration rates are reduced and fresh air is supplied, filtered and post-heated by a MVHR unit.
Why do we need greater energy efficiency?
This Passivhaus study comes at a time when the English Housing Survey has shown that English housing stock is becoming more energy efficient. In their annual report, they found that almost a quarter of all dwellings (23%) now fall into the A to C energy bracket, a sharp rise from the 2% back in 1996.
For landlords, owning and renting out an energy efficient home has large advantages, as it will be far easier to attract tenants who are looking to save money on their bills, or are currently living somewhere that is inefficient. For tenants, the low cost of bills is obviously appealing, as it will reduce their financial outgoings each month.
With fuel prices continuing to rise, it has become more important than ever for us to reduce our dependence on fossil fuels. The low heating demand of Passivhaus homes makes this possible, only requiring 15kWh per square metre per year. In real terms, this means that heating bills are reduced by a factor of 5-10.
Passivhaus claim that one of their 70m2 homes with gas heating could spend as little as £25 on space heating each year.
How to achieve the Passivhaus standard
Achieving this standard in the UK involves a significant amount of work, as is shown by the Passivhaus case studies. However, it typically includes:
- High levels of insulation
- Windows with insulated frames
- Airtight building fabric
- ‘thermal bridge free’ construction
- A mechanical ventilation system with highly efficient heat recovery
- Design using the Passive House Planning Package (PHPP)
If you’re interested in the work of Passivhaus, or want to see details about some of the 37,000 buildings they’ve designed, then you can find more information here.