Using CHP to achieve compliance with the renewables requirement of NZEB is an attractive option. If there is Natural Gas available at the site location and Gas boilers are to be used to provide space and DHW heating then CHP can easily be used as part of the centralised heating system. Glenergy supply CHP units ranging from 14W - 100 Kw thermal output from Senertec (the Dachs) and Remeha (RGen).

Design Considerations

Sizing CHP systems is important to get correct. CHP systems offer best value when they operate for long hours so they are constantly producing heat which needs to be used. For this reason they should be sized to address a constant thermal base load present in the building. Loads for DHW are usually addressed best as they are a daily constant and present Summer to Winter.

CHP and Heat Pumps

When the CHP unit is producing heat it is also producing electricity. Again for best value to the client the electricity should be used on site and not exported to the grid as this represents a loss to the client. Constant electrical loads in the building such as lighting, pumps, elevators can benefit from the electricity from CHP unit but it can also be heplpful to combine smaller CHP units with heat pumps as the heat pumps will provide a home for the electrcity produced by the chp unit. This allows for smaller CHP plant to be designed which eliminates wasted energy and increases value to the client.
  • Renewables will need to cover a substantial part of energy use in NZEB buildings (up to 20% on non domestic)
  • CHP can provide full compliance with NZEB renewables requirements.
  • CHP can be combined successfully with Heat Pumps as the heat pumps use the electricity produced by the CHP
  • Base load considerations should be taken into account when designing CHP size.

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