PassivHaus

Making a house as zero carbon is much easier when it uses minimal energy. This is particular true when it comes to space heating which has traditionally been with gas or oil central heating. Building to Passive House Standards means a maximum space heating demand of 15kw/m2 which is 90% less than a typical house. The remaining heating requirements are then easily met with modern far infrared heating which can be 100% zero carbon when combined with a renewable electricity supply. 

 

PassivHaus standards are achieved using the following principles

 

  • Airtight  building envelope - high performing tape used on joins and fan pressure test to prove air change 0.60m3/hm2 (@50pa). Entrance halls with internal and external doors useful to avoid loss of heat when entering the building.

  • Insulation for wall, floor and roof insulation typically 300mm with high R value.

  • Solar Gain - Predominantly south facing windows with triple glazing, insulated frames with low U value and shading to avoid overheating when sun is low.

  • Thermal bridging avoidance by redesigned corners, offsetting joist between interior and exterior layers.

  • MVHR (Mechanical Ventilation with Heat Recovery) that provides very healthy building (standard is 75% efficiency but best to aim for 95% efficiency).

  • Due to low energy required, this is supplied by occupants and appliances for typically 9 months of the year. Therefore only a small heating system is required for 3 months in the winter.

  • The Passive House standard doesn't insist on renewables as the heating source but it makes a zero carbon house easily achievable by using modern infrared heating panels and immersion with solar diverter for domestic hot water. The renewables can be supplied with a 100% renewable grid contract or self generation. Roof top solar can achieve 75% self sufficiency and 100% when combining solar/wind/battery technology.

 

For further information here is a practical video illustrating passive building design.

https://youtu.be/Hz6qomFM_dw

PHPP design spreadsheet is used to calculate thermal gain, shading requirements, space heating and ultimately Passive House Certification. 

http://www.passivhaustrust.org.uk/design_support.php