Diary Entry No.20 - Hot Water and Space Heating Installations

Space Heating

he applied Passivhaus approach dramatically reduces the demand for space heating which means the house does not require a conventional central heating system. The space heating demand will be 14kWh/(m2/a) for the entire house. Compare this to 50kWh/(m2a) for a typical new build dwelling, or even 100kWh/(m2a) for an older dwelling, the saving is evident.

The dwelling will also be heated passively, utilising solar gains, energy given off by the day to day activities and recycled using the ventilation system. This system will transfer a calculated amount of heat throughout the house with smaller rooms needing no additional heat source due to the delivered temperature of the warm air. These ‘passive’ heat gains go a long way towards maintaining a comfortable temperature within the dwelling. The small amount of additional heat required in the winter months must be provided from an external source.

In this case we have provided the additional heating in the living room by means of a 5kW wood burning stove. This is a RIKA Vitra passive house wood burning stove which is located in the double height living space. It is unique in that it is independent to the air in the room as it has its own ducted air source direct from outside. It has the capacity to provide active warmth to a space of 50-110m3 using very low amounts of energy, whilst releasing minimal emissions. The following photography illustrates the RIKA Vitra passive house wood burning stove.

In additional to the wood burning stove, three Fondital towel radiators have also been installed in the bathrooms and ensuites to eliminate the problem of how to dry towels and perhaps clothes as there are no conventional radiators located within the passive house. These radiators are supplied from the 300 litre thermal store and are an efficient way of utilising the additional heat generated by the solar panels and heat pump.

 Solmatix X3 Combi PLUS with Solar & Independent Space Heating diagram

Solmatix X3 Combi PLUS with Solar & Independent Space Heating diagram

Hot Water Heating

The hot water is heated by means of two Solmatix solar panels installed on the south facing roof in the summer; these connect to a 300 litre thermal store. The ESP Ecocent indirect unvented air source heat pump will economically provide a back up for hot water production during the winter months. Solmatix provided and installed both the solar panels and the heat pump, alongside offering us vital advice and helping to produce an economic, low energy heating strategy for the passive house.

The following photographs illustrate the solar panels when there were being installed, which occurred as the roof was being slated to prevent any retrofitting issues. The second photograph illustrates the air source heat pump as installed.

 Solar-thermal panels

Solar-thermal panels

 Hot water cylinder with integrated air-source heat pump

Hot water cylinder with integrated air-source heat pump

Overall we are pleased that our extensive research and design development has resulted in a comprehensive highly energy efficient hot water and space heating system.

We are pleased that the comprehensive ventilation, hot water and space heating installations have come together so successfully on site. We are nearing the end of the passive house construction and in the next diary entry we will discuss some architectural details which we haven’t yet touched upon.