img(height="1" width="1" style="display:none" src="https://www.facebook.com/tr?id=2939831959404383&ev=PageView&noscript=1")

Heat pumps: how to cut energy bills by up to 80%

Header Image

Words:
Wendy Perring

Our winter series on ways to keep homes warm without killing the planet continues with an assessment of ground and air source heat pumps. PAD Studio shares the fruits of its experience

The Challenge

Both ground and air source heat pumps (GSHP & ASHP) employ heat exchange as the means of creating energy; the ASHP uses energy from the air, and the GSHP uses solar energy stored below the ground.

In the cold damp UK climate, an ASHP can suffer energy losses in the winter as it struggles to extract heat from the cold air and prevent the heat pump from icing up, whereas the temperature below ground is relatively stable and more efficient.

Depending on the energy efficiency of the building (which determines the amount of input heat required) the energy bills of a house that uses a GSHP should be 70-80% lower than one heated traditionally. Alongside the monetary saving in fuel bills is a vital reduction in carbon emissions and, as the energy is generated on site transference losses at source are minimised.

  • Gardeners Cottage, PAD Studio Hampshire Architects.
    Gardeners Cottage, PAD Studio Hampshire Architects. Credit: Jim Stephenson
  • Gardeners Cottage, PAD Studio Hampshire Architects.
    Gardeners Cottage, PAD Studio Hampshire Architects. Credit: Jim Stephenson
  • Gardeners Cottage, PAD Studio Hampshire Architects.
    Gardeners Cottage, PAD Studio Hampshire Architects. Credit: Jim Stephenson
  • Gardeners Cottage, PAD Studio Hampshire Architects.
    Gardeners Cottage, PAD Studio Hampshire Architects. Credit: Jim Stephenson
  • Gardeners Cottage, PAD Studio Hampshire Architects.
    Gardeners Cottage, PAD Studio Hampshire Architects. Credit: Jim Stephenson
  • Gardeners Cottage, PAD Studio Hampshire Architects.
    Gardeners Cottage, PAD Studio Hampshire Architects. Credit: Jim Stephenson
  • Gardeners Cottage, PAD Studio Hampshire Architects.
    Gardeners Cottage, PAD Studio Hampshire Architects. Credit: Jim Stephenson
1234567

The Approach

The GSHP is more expensive in capital costs but is almost maintenance free, has no more noise pollution than a domestic washing machine – and when we were installing it at our project for a down-sizing couple with green ambitions, The Gardener’s Cottage, the government’s Renewable Heat Incentive repaid the capital cost of the installation and heat pump over a period of 10 years.

Vertical GSHP systems sit in a vertical bore hole near the house. Boreholes can go down 80m-120m depending on soil conditions but the disruption to the site is minimal (which makes them an excellent solution for existing buildings). Conversely, horizontal GSHP systems require a series of trenches which are only around 1.2m deep – these are cheaper to install and work very well if you have a lot of level land, but they do require a lot of space as the trenches need to be spaced out to ensure maximum efficiency.

  • Gardeners Cottage, PAD Studio Hampshire Architects.
    Gardeners Cottage, PAD Studio Hampshire Architects. Credit: Jim Stephenson
  • Gardeners Cottage, PAD Studio Hampshire Architects.
    Gardeners Cottage, PAD Studio Hampshire Architects. Credit: Jim Stephenson
  • Gardeners Cottage, PAD Studio Hampshire Architects.
    Gardeners Cottage, PAD Studio Hampshire Architects. Credit: Jim Stephenson
  • Gardeners Cottage, PAD Studio Hampshire Architects.
    Gardeners Cottage, PAD Studio Hampshire Architects. Credit: Jim Stephenson
  • Gardeners Cottage, PAD Studio Hampshire Architects.
    Gardeners Cottage, PAD Studio Hampshire Architects. Credit: Jim Stephenson
  • Gardeners Cottage, PAD Studio Hampshire Architects.
    Gardeners Cottage, PAD Studio Hampshire Architects. Credit: Jim Stephenson
123456

The Result

On average the installation cost of a vertical GHSP is around £25-50,000 and a horizontal system around £15-25,000. An ASHP of the same capacity is around £6-10K. All heat pumps still require electricity to run them (which, like those at Gardener’s Cottage, can be generated via photovoltaic panels). For every unit of energy inputted, around four is generated via the heat pump (this is called the coefficient of performance; CoP) and this will drop slightly over the lifespan of a heat pump. The CoP of a GSHP is slightly higher over its lifespan than an ASHP and in our experience over the last 10 years of using both, they tend to have a longer lifespan and fewer maintenance issues.

Wendy Perring is director, PAD Studio

Read more on architects and energy efficiency.

Latest

Housebuilders are increasingly turning to large-scale 3D printing to deliver low-cost homes, but do the reported benefits around speed and reduced labour and waste add up? Stephen Cousins reports

Housebuilders are increasingly turning to large-scale 3D printing to deliver low-cost homes

Design an inclusive on-campus cricket centre, help establish a national waterfront destination, create a display piece for a unique urban environment - some of the latest architecture contracts and competitions from across the industry

Latest: cricket and education centre

Dominic McKenzie Architects’ Segmental House extension combines nods to Scandinavian modernism with references to the arches and Flemish bond of the existing building

Dominic McKenzie Architects’ extension combines Scandinavian modernism with references to the existing building

Kazuyo Sejima and Ryue Nishizawa, who set up SANAA 30 years ago, talk about how nature is both the context and inspiration for most of their work and how they aim to make architectural spaces where people come together

Practice founders Kazuyo Sejima and Ryue Nishizawa talk about their work over the past 30 years

While revenue growth hasn't kept up with the rising costs of running a practice, a surge in overseas work could help turn things around for UK practices, says RIBA head of economic research and analysis Adrian Malleson

A surge in overseas work could help boost revenue growth for UK practices