Thinking about building your own home? Wanting it to be energy-efficient? Then why not look into the option of building a home that has maximum energy efficiency – achieving a Passivhaus status? The name Passivhaus is derived from a German standard for buildings that are built to be incredibly energy efficient. The house has an inside climate that is comfortable for all inhabitants, but one that isn’t obtained using cooling or heating systems.
The heat demand that is required within a home that would normally be obtained through heating sources such as boilers and fires is instead sourced from extracted air, the sun, household appliances and the occupants of the passive house – reaching much of the demand for heat. Any further heat that is required is acquired through the air that has been supplied; providing adequate enough heating because the house itself has been design so as to lose minimum heat.
In order to reach this incredibly low level of heat loss, the house has to be built to be exceedingly air tight, with a high level of insulation. Windows, floors and walls (passive solar gains) are also used for storing and distributing solar energy during the winter months; getting rid of it during the warmer months. The house will also require energy-efficient window frames and glazing and will also need to have good air quality which is obtained through a mechanical ventilation system, with heat recovery. It also goes without saying that light fittings and appliances will also need to be of low energy consumption.
The lower energy demand that is still required with the house can be supplied through other renewable energy sources, such as ground source heat pumps and solar panels. Interestingly, windows in these types of houses can be opened but shouldn’t need to be as the ventilation system will ensure enough fresh air is distributed into the house.
Why should I choose to build a passivhaus?
Firstly, you will be doing your bit for the environment, by reducing the carbon dioxide emissions that are used in running your home, consequently preserving the amount of fossil fuels remaining.
Secondly, your household bills will reduce dramatically. According to the Passivhaus Trust, when built correctly, a passive house should reduce space heating requirements by a whopping 75% compared to your standard new build – and these are somewhat energy efficient anyway! Evidently, there will be a greater investment involved in building the house initially, but the savings in the long run could mean it is a worthwhile investment.
What’s more, you won’t suffer with draughts in this type of house and the heat will be evenly distributed to create a comfortable environment. Equally, if you suffer from allergies such as hay-fever, the filters that are used within the air system will prevent things such as dust and pollen from entering the home.
How would we build a Passive House?
If building a passive house sounds like something you’d like to do, you will first need to find a site that will hold your desired house and seek to find out if planning permission for such a design is likely to be granted. The design will have to take into account the need for the routes of the ventilation ducts, south-facing windows and many more factors that are essential in a passive house.
There is a specific package that is used within the designing procedure; called the Passivhaus Planning Package (PHPP) and this will allow your architect to evaluate how energy efficient the house will be based on how it is ventilated, designed and what climate it is within. You should also seek to find a consultant or designer that is certified within Passivhaus construction.
In order to gain a certificate to say that your house is a Passive House, you will need to apply through The Passivhaus Institut, the Scottish Passive House Centre, Warm or BRE website.
Your house must also meet the following targets:
• Specific primary energy demand: equal to or less than 120kWh/m²/year
• Specific heating load: equal to or less than 10W/m²
• Specific heating demand: equal to or less than 15kWh/m²/year
The energy demand will also need to include fans, domestic hot water, space heating, pumps, lighting and all other appliance consumption.
