Renewable energy 

One of the key features of this Passiv Haus is that it is not only designed to meet the stringent requirements of the the Passiv Haus Institut, but also to generate its own energy. By making enough energy to power the whole house the property becomes Carbon Neutral.

The main two sources of energy required in a house are heat and electrical power. To accomplish this, the house was designed to take two distinct renewable technologies. Firstly, solar thermal energy to provide hot water for washing etc and secondly, photovoltaic (PV) energy to provide electricity for the heating and ventilation systems as well as for household appliances etc.

The most efficient domestic solar thermal system is an evacuated tube array. This is linked up to a thermal store where the suns energy is stored for use when needed. During the winter, this might need to be backed up using an immersion heater, but the energy for this can come from the PV panel.

The PV system works by generating energy when the sun shines and a two way meter allows for this energy to be sold to the national grid during the generating period. At night, when we generally require more electrical power (lights etc.) the house automatically starts to import energy from the grid. This balance should mean that overall during the day / year that the house uses as much electrical energy as it produces. This balance (combined with the solar thermal generation) means that the house is Carbon Neutral.

As stated before, in order for this to work, the demand for energy must be kept to an absolute minimum, hence the structure of the house and the energy efficient equipment that it used throughout. (All white goods are A + rated, lights are low energy and the Mechanical Ventilation and Heat Recovery Unit is over 90% efficient)

The following shots show the solar thermal units being fitted and also them arranged just above the PV panels. Note that the solar thermal tubes are raised to a steeper angle so that they run at their maximum efficiency, especially for the winter months.