Heat pumps cross the final frontier
Energy efficiency is ever more imperative, as not only do environmental initiatives like Energy Performance Certificates drive the move towards low carbon, but also commercial buildings, like domestic homeowners, are seeing their fuel bills rocket. Heat pumps can make a substantial contribution to reducing energy usage and in more ways than straightforward space heating.
Going for green
So how does the move towards low carbon affect commercial buildings managers? One of the most recent changes is increased transparency on energy consumption, aimed at encouraging a ‘greening’ of systems as occupiers are expected to favour better-performing buildings, with lower running costs.
The requirement for Energy Performance Certificates has been extended. From April 2008 these have been a requirement upon construction, sale or lease for all non-dwellings over 500m², but from October 2008 this extends to all non-domestic buildings, covering everything from small high street retailers to airports. The Certificate gives an energy rating, advice on improvement and a rating from A to G, with A the best.
In the public sector, Display Energy Certificates have been required since April 2008 for all public authority buildings and institutions providing a public service with a floor area over 1000m², including council offices, schools, hospitals and any other publicly owned buildings accessed by the public. These Certificates are based on actual energy consumption over a three year period (if available) and give an operation rating.
In addition, in the new build sector, the Merton planning rule is being adopted by an increasing number of local authorities in the UK – currently around 100 have either fully adopted it or feature it in their draft Local Development Frameworks or Supplementary Planning Documents.
Named after the London borough which was the first council to incorporate the government’s Planning Policy Statement 22 guidance on incorporation of renewables in its planning legislation, the Merton rule requires that for new non-residential development above a threshold of 1,000m², at least 10% of all energy production comes from renewable energy equipment on site.
To comply with this obligation as well as respond to the pressure to display high levels of energy efficiency, heat pumps are an increasingly common solution, either as standalone solutions, or used in conjunction with standard boilers for top-up heating when required.
Keeping it cool
A major advantage of heat pumps for commercial premises is their ability to cool a space, as well as heat it. The operation of heat pumps can be reversed to draw heat from the building and transfer it to the environment, where it is harmlessly stored for when it’s needed. Heat pumps either use passive cooling, where cool water is circulated through the system without the compressor being used, reducing the ambient temperature by a few degrees, or dynamic cooling, where the compressor and heat pump cycle are reversed to extract heat from the air in the building, creating a greater cooling effect.
So instead of maintaining an air conditioning system in addition to the heating system, a heat pump can do both. And unlike variable refrigerant flow air conditioning systems, heat pumps are hermitically sealed only needing minimal and straightforward maintenance. Heat pumps up to around 30kW typically fall outside of the F Gas regulation for mandatory annual checks.
In a useful variation on this process, Dimplex’s new TER+ large capacity units incorporate a heat recovery function to utilise the waste heat produced in cooling mode to heat water, either for sanitary hot water (for example, for washrooms or showers) or for low grade warmth for swimming pools, making these high capacity models ideal for leisure centres and health clubs.
Lease of life
Costs for installing heat pump systems vary enormously, but according to the Energy Savings Trust, a good rule of thumb is around £800-£1400 per kW of peak heat output, excluding distribution system. Due to this front-loaded capital outlay, the UK market is starting to look at leasing arrangements. Once installed and commissioned, the savings made on energy bills can be put towards the cost of leasing the equipment, so that in fact the system pays for itself to a large extent, while ticking all the boxes on the reduced carbon emissions front.
Due to the fact that a substantial proportion of the cost of a system comes from the collectors buried in the ground and the distribution system (i.e. underfloor heating) embedded in the fabric of the building, it remains to be seen exactly how these schemes will work in practice, but Dimplex, for example, is putting a leasing scheme in place which looks at each customer’s requirements on an individual basis, working with the client to make low carbon heat possible for every building.
Heat pumps in action
Dimplex heat pumps have been used in a wide variety of commercial premises in both public and private sector. With grants from the Government’s Low Carbon Buildings Programme Phase 2 now offering subsidies of up to 50% to public sector and not-for-profit projects, Dimplex and its network of approved heat pump installer partners have been involved with a wide range of organisations applying for heat pump funding, with projects including schools, libraries, places of worship, community halls and social housing.
In the swim
A Dimplex ground source heat pump has been installed at Stromness Swimming Pool & Fitness Suite on the mainland Orkney Islands to provide low cost, low carbon heat for the pool itself. Despite the northern latitude, the island environment with its proximity to the sea means that the environmental temperature is relatively stable, so there’s plenty of low grade heat available, which will be used to warm the water in the public baths.
National Trust recycles heat
A Dimplex air source heat pump is utilising the warm air recovered from the kitchen fridges to keep customers warm at Crofters, a courtyard restaurant at Trelissick, a National Trust estate near Truro in Cornwall. The heat pump has an output of 11kW and runs extremely efficiently as the external fridge condensers from the kitchens have been grouped together with the Dimplex air source heat pump in an insulated outbuilding. This means the air to water heat pump is given a kick start by the warm air expelled from the kitchen fridges, which substantially raises the ambient air temperature.
Low carbon community centre
The North Shields Meadows Neighbourhood Centre’s Terra Nosta (our earth) project has installed a Dimplex 45kW ground source heat pump as part of its vision to be carbon neutral. The ground collectors were installed horizontally, due to the large area available under what will become the organic vegetable patch; an area of 1800m2 was dug to a depth of 1.2m to install 3km of pipe in the ground to collect the heat. The 45kW SI 50TE ground source heat pump system has been planned to feed in to both the heating system and hot water tanks at the centre.
With legislation on energy efficiency and the incorporation of renewables set to become increasingly rigorous in the future, now is the time to explore the benefits of heat pumps, bearing in mind the flexibility of this low carbon technology is capable of a lot more than just providing space heating.