Passive design is design that does not require mechanical heating or cooling. Instead they use nature for cooling and heating. Studio Negri were recently awarded certification in the design of passive houses, from the Passivhaus Institut, Darmstadt, Germany.
Advantages of Passive Houses
- Increases natural comfort
- Reduces bills
- Decreases greenhouse gas emissions from heating, cooling, mechanical ventilation and lighting.
Passive Houses incorporate very high standards of insulation. This reduces the amount of heat lost through the building fabric to the lowest possible levels. When achieving these very high standards of insulation the purpose provided heating requirement, even on the coldest days, is reduced to a minimum and hence it is possible to adequately heat the dwelling by just preheating the fresh air entering the rooms.
Core elements for optimal performance of a Passive House
1. Optimising a building’s shape and orientation to reduce heat loss and maximise solar gain
- Designing compact forms with minimal surface to volume ratios.
- Sizing south facing glazing to capture solar heat gains.
- Minimize over shading through other buildings or objects.
- Consider forms of shading to avoiding summer overheating.
- Huddling buildings together to reduce exposed areas.
2.Super insulating the building fabric
- Low wall, roof and floor U-values, typically 0.15 W/m2K or lower, about 300mm of insulation.
- Thermal bridge-free construction.
- The thermal envelope has to be designed and build to highest specifications.
- High performance glazing with whole window U-values, typically 0.8 W/m2K or less (triple glazing).
3. Reducing ventilation heat loss with an airtight fabric
- Reduce air permeability below 0.6 ach-1 @ 50Pa (6-10 times better than standard UK construction).
- Air tightness foil for all joints of building components.
- Performance guarantee by air permeability testing.
4. Providing continuous fresh air with mechanical ventilation and heat recovery
- An 80-90% efficient heat exchanger and mechanical ventilation ensure that the home is superbly ventilated without increased heat loss.
- Correct design and installation of the low power fans and ducting ensures the system runs silently.
- Some MVHR systems have a summer bypass for bypassing the heat exchanger in summer.
- Occupants can always choose to additionally ventilate the house by opening windows.
5. Reducing primary energy demand to less than 120kWh/m2 /year and applying renewable energy systems when appropriate…
- Specify low energy light fittings and appliances.
- Insulate domestic hot water pipes and cylinders.
- Provide hot water with solar thermal panels and storage.
- Further reduce CO2 emissions with renewable energy systems