Before starting your project, it’s important to spend time thinking about and write down why you want to do it. Note down what functionality you want at the end of the project and how you plan to get there. Time spent in the planning stage will save time, and possibly money, later in the project and avoid disappointment at the end. This section explains what you need to think about, the information you should give and the questions you should ask an installer or design consultant.
What is the goal of the project?
At the start, ask yourself:
- What is the goal of the project?What would your group consider a successful outcome?
- Is the aim purely to decarbonise your heating system?
- Is it to improve the thermal comfort for users who currently find it cold?
- Are you fighting damp?
- Do you want the lowest cost or the lowest running cost?
- Do you need the heating system to react quickly for intermittent use?
- Do you want to be able to control it remotely?
Here is an example of what a goal might be:
“We want to make sure that the large hall is warm enough for a yoga group to use in winter. We want to be able to use a mobile app to turn the heating on remotely and in advance of the class so that the room is warm when the users arrive. We don’t want users to fiddle with the settings and leave it on after they have left. We want the heating system to be low carbon and, while running costs can be covered by revenue, capital cost must be minimised.”
At this point, your goal might not include anything about solutions, but with a wish list in place, you can move on to think about the technical aspects of the system.
Understand your existing system
Having the details of your existing heating system or getting someone to survey it and provide this information is vital. This information will allow you to understand if a heat pump can be a simple add-on or if the entire system needs to be rethought.
If there is an existing heating system, what is it? If it’s a wet system (ie there are pipes connecting to radiators or underfloor heating), then it should be easy to connect an air-to-water heat pump.
If it’s a wet system, then at what temperature does it operate? If the flow temperature is above 65°C, then you may have to consider installing larger radiators so that you can use a lower temperature for maximum heat pump efficiency.
If users have reported that the system takes a long time to heat up or struggles to maintain heat then you might have to consider larger radiators and confirm that the heat source and water pump are sufficiently sized.
If the heating system generates domestic hot water via a hot water cylinder, then this will have to operate at up to 65°C to prevent legionella. This would result in the heat pump operating at a lower efficiency. Consider if the hot water demand justifies this inefficiency; electric heaters at each tap might be better if use is infrequent.
If you have radiant electric heaters, then you may be used to the heat coming on instantly. To come close to matching that, you might want to consider an air-to-air heat pump system which transfers heat to the room and circulates it quickly. Since heating all the air in the room takes more energy than heating people with a radiant heater, changing to a heat pump may not be the right option for a large, infrequently used space. It’s worth getting help from your installer or a consultant to answer these questions.
If you have electric storage heaters then you already have a low-carbon heat source and may be benefitting from low night-time energy tariffs if they suit your usage patterns. Carefully consider whether the more efficient heat pump stacks up against the cheaper energy. It’s worth getting help from your installer or a consultant to answer this.
If you have electric panel heaters, you already have a low-carbon heat source. A heat pump installation can be two to three times more energy efficient but with a high capital cost. Consider if the savings over the lifetime of the heat pump balance out the installation cost.
Influence of building usage
If you have a building that is occupied for long periods of the day, several days a week, then a system which heats up slowly and runs steadily and efficiently would be suitable – such as underfloor heating. If you have a building that is used for a couple of hours on a few evenings a week, then a system which heats a room quickly may be more important, such as an air-to-air heat pump. If the pattern of use may change in the future, then locking into a “slow” system may not be advisable.
Influence of building layout and zoning
In a building with several rooms, you may want to be able to heat different areas of the building as needed. For example, a meeting room in a community building may be used often, but you wouldn’t want to heat the adjacent sports hall at the same time if it wasn’t being used. In this case, a zoned system is ideal. Map out which rooms you would like to heat separately and which spaces (like a vestibule) you would like to heat together.
How big does the system need to be?
A simple approach to this question for some buildings would be to replace like with like eg replace a 50kW boiler with a 50kW heat pump. However, this might leave you with an expensive and over-sized system. Heat loss calculations should be performed for all buildings, and hot water demand estimated if needed.
Installers may be able to do these calculations and this task should be included in their contract. These calculations could be expanded to estimate the annual energy consumption, helping compare current and future costs.
Do you need to upgrade any of the fabric of the building?
Improving the insulation properties of your building will always reduce your energy consumption. It’ll also reduce the peak heat demand, which might affect your system choice. Some insulation measures, like adding mineral wool to a loft, are cheap, effective and relatively easy. Others, like new glazing or external wall insulation, are more costly and difficult to do.
Each option should be examined on a case-by-case basis, comparing the likely energy cost savings over a year against the installation cost. In a little-used building, the energy saved will likely be small relative to the outlay, but in a building used all day, every day, the savings will likely result in a reasonable return on investment. These calculations should be done by someone competent in heat loss calculations and annual energy usage assessment.
How many trades will be involved?
As the scope of the project takes shape, you will be able to see how many different trades might be required. A heat pump installer and a certified electrician are obvious, but the list might grow to include, for example:
- a gas-safe installer to remove gas appliances
- a builder to form and make good holes in external walls
- a joiner to form pipe boxouts
- a decorator to make good finishes where old installations have been removed
- a flooring specialist to lift and replace floors removed for pipe installations
- a cavity-wall insulation contractor
- a glazing contractor
- an underfloor heating installer.
If the list is long, then you must consider whether the heat pump installer can manage all the subcontractors in a large project, or whether you can manage several contracts or if it might be sensible to employ a main contractor.
Regulatory implications
You will need a building warrant for the work, but this is unlikely to affect your choice of system.
You may need planning permission, so contact your local planning authority about any requirements they have. Consider the location, appearance and noise of any piece of outdoor equipment, particularly if your building is close to residential neighbours.
If your building is listed or in a conservation area, then the planning permission authority will also consider:
- the appearance and location of the unit
- its physical connection to the building
- the impact of any fabric upgrades that you may be considering.
Although it’s unlikely that you will have a heat pump that contains F-gases today, be aware that you will have to comply with the F-gas regulations. Other refrigerants may have to comply with future regulations relating to PFA s.
Who can help with all these questions?
This guide is helpful, but it can’t replace a two-way conversation. Talking to other community groups and reading their case studies can give you inspiration and reassurance about the project. An engineering consultant can give you unbiased information and advice, especially during the early stages of feasibility planning, but their fees are a cost to consider.
Manufacturers and installers can offer detailed advice on their products and their installation, often at no cost. However, they may not be advise on other products or help you compare different technologies. Funding bodies, including the Scottish Government’s Community and Renewable Energy Scheme (CARES), can provide project planning guidance, helping you to navigate funding and avoid project pitfalls.
