Ground Source vs Air Source Heat Pump – Which is Best?

14 January 2019
by Mike

Our current project features underfloor heating, an open plan area of approximately 120 m2. We have 120mm Celotex in roof, 140mm in walls and 100mm between concrete slab and screed, so it' a well-insulated structure.

We have the space to install a ground source heat pump (GSHP), but not quite the budget. We are considering an air source heat pump (ASHP) instead, but seen quite mixed reviews of both types of pump.

With this amount of insulation, is it worth going for GSHP or is ASHP a more cost effective method? In light of the system maybe not needing to be running all the time, which one is better for us?

Happy to consider other options, but there is no gas on site - only electricity.

2 Answers

  1. Low heat demand -> impact of system relatively high. So that says air source heat pump (AHSP).

    ASHP is not as efficient in midwinter as a ground source heat pump (GSHP). But, in theory, your heat demand is so low that it would not justify the extra cost and environmental impact of GSHP.

    Consider supplementing with a small woodburning stove in midwinter. You could also hook it up to a hot water cylinder if this could take additional input.

    Nigel Griffiths, Build It expert

  2. Sofia Delgado says:

    Hi Mike,

    To add to Nigel’s answer, I can recommend you read his article How to Power an Off-Grid House, where he mentions other options available to heat up your home if mains gas is not an option. One of them is installing a biomass boiler.

    Nigel will be at the Build It Live shows talking about the relative sizes of impact in use and in installation when it comes to this technology. He will also take part on the Heating Debate next to David Hilton to discuss and compare all the options available.

    Nigel will also be at the Ask our Experts area, giving free one-to-one advice if you would like to have a chat. And David Hilton will be at the Heating Advice Clinic, our latest feature to help self builders and renovators choose the right setup according to their needs.

    You can find more information about the shows and the exhibitors at

    Best wishes,

    Sofia Delgado, digital assistant editor

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