Sizing up the right heating for your home

Published 29 August 2022

New Zealand homes are notoriously under-equipped for the winter, and a lot of people struggle to keep their energy costs down over the colder months.

This is generally made up of a few factors such as poor insulation and damp conditions, but inadequate heating is a big part of this too. To the point then, "are my heat sources sufficient?"

Heat pumps are now a popular addition to most homes, given that they deliver heat into the home generally at 3:1 above the kW drawn off the grid, i.e., for every 1kW of energy drawn they give out 3 KW’s of heat, but if they aren't sized correctly you may find that they underperform, or become costly to run. To size an area for a heat pump:

• First take the m² floor area, e.g, (5m x7m lounge) then multiply by ceiling height (standard homes are 2.4m).

• The next thing to calculate is the amount of kW's required given the expected performance of the home. For a home that is insulated above and below, walls and double glazed, use a factor of 50. Increase this by 5 for anything that may be lacking in the home (no insulation or double glazing requires a factor of 65.) For this example, the heating required for 84m³ area in a well-insulated home is 4.2kW, whereas a home lacking these measures will require 5.5kW for the same area. Then choose a heat pump that is a bit higher than your calculation so that it’s not overworked. In the above example, a 4.5 - 5kW heat pump is recommended.

When sizing for a bedroom (where heat pumps are generally too large) using our radiant heaters, measure only the floor area, then multiply the m² by 0.8. Example being a 20 m² bedroom x 0.8 would require 1.6kW. Otherwise, use the heat pump sizing method if using a convection heater. If you aren't sure about getting it right then book a free heating assessment with us and we can give you all the options. Hope this helps, stay warm this winter!