Heat pumps in commercial buildings
A commercial heat pump is usually a carbon, compliance or plant replacement decision rather than a savings one.
What it actually is
A heat pump moves heat rather than burning fuel. Each unit of electricity delivers several units of heat. How many depends on the temperature it has to reach.
Electricity costs more per unit than gas. A building with large emitters and low flow temperatures closes that gap. A building designed around a hot boiler usually does not.
A heat pump moves heat rather than making it. It takes low grade heat from the outside air or from the ground and lifts it to a temperature useful for heating the building. Because it is moving heat rather than burning something, each unit of electricity delivers several units of heat.
The size of that multiple is the whole argument. It falls as the temperature the system has to reach rises. A building with large emitters, decent fabric and a low flow temperature lets a heat pump run efficiently. A building designed around a hot boiler and small radiators forces it to work at the top of its range, where it is least efficient.
Then there is price. Electricity costs materially more per unit than gas in the UK, so a heat pump has to be several times more efficient than the boiler simply to break even on running cost. On a well suited building it clears that bar. On a poorly suited one it does not.
This is why a commercial heat pump is usually a plant replacement, carbon or compliance decision rather than a savings one, and why anybody presenting it purely as a way to cut your bills is either optimistic or selling. The honest version is that the right moment is when the existing plant is at the end of its life and you have to spend money anyway.
Which buildings it suits, and which it does not
It suits buildings with an ageing heating system due for replacement anyway, buildings with a carbon commitment, and buildings where the fabric is already reasonable.
It suits you less as a cost saving exercise. Commercial payback is often twenty years or more.
- Buildings with ageing heating plantGood fitThe comparison is not against your current bill. It is against the cost of a like for like replacement you are about to buy anyway.
- Modern offices with underfloor heating or fan coilsGood fitLow flow temperatures and good fabric are exactly the conditions a heat pump wants.
- Buildings needing both heating and coolingGood fitA reversible system does both from one plant, which changes the economics considerably against a boiler plus separate cooling.
- Schools and public buildingsDependsOften carbon or funding driven. Fabric condition and emitter sizing decide whether it will run well in practice.
- Older offices with small radiatorsDependsAchievable, but emitters usually need upsizing, and that cost belongs in the comparison from the start.
- Large uninsulated warehouses with high bay heatingRarelyHigh heat loss and high flow temperatures. Do the fabric and the destratification first, and reassess after.
- Process heat above normal heating temperaturesRarelyStandard commercial heat pumps do not reach industrial process temperatures. That is a different specification entirely.
- Sites with no spare electrical import capacityRarelyA heat pump adds load. If the connection is full, the reinforcement cost can exceed the plant cost.
What it typically costs and saves
- Installed cost
- An installer prices this one
- Seasonal efficiency
- 2.3 to 3.4 units of heat per unit of electricity
What drives the variation
- •Thermal output required, which depends on heat loss and not on the rating of the old boiler.
- •Whether emitters, pipework or the distribution system need changing to run cooler.
- •Air source or ground source. Ground source removes the noise and efficiency variation but adds substantial groundworks.
- •Electrical works, including any supply reinforcement or switchgear.
- •Whether cooling is included, and whether the system is replacing a separate cooling plant.
- •Controls, metering and commissioning, which are frequently under specified and then added later.
How this appears on your building
- No heat demand is held for this building, so no saving has been produced.
- The age and condition of the existing plant has not been recorded.
What decides whether it works on your building
The flow temperature the building needs
This is the single biggest determinant of efficiency and therefore of running cost. It is set by the emitters and the heat loss of the building, not by the plant. A heat loss survey, room by room, is the basis of a credible design.
Spare electrical import capacity
You are moving load from gas to electricity. Check your agreed capacity and your measured peak before anything else. A capacity upgrade can be the largest single line in the project.
The age and condition of the existing plant
If the boiler has a decade left, the case is weak. If it is failing, you are comparing two replacement options rather than comparing change against no change, and the numbers look completely different.
Fabric condition
Insulation reduces the heat the building needs, which lets the pump be smaller and run cooler. Fabric first is not a slogan here. It changes the size and the running cost of the plant you buy.
External space and noise
Air source units need free air flow and clearance, and they make noise. Boundary noise limits are a planning matter and can dictate where a unit can go, or whether it can go at all.
Hot water demand
Buildings with a real hot water load, such as care homes, hotels and leisure, need a strategy for reaching storage temperatures safely. That usually means a specific arrangement rather than a single unit doing everything.
How long it takes and what it disrupts
Design stage
Heat loss survey, emitter assessment, electrical capacity check, noise assessment and, in many cases, planning. This is the longest and most important part, and cutting it short is the most common reason installations disappoint.
Enabling works
Emitter changes, pipework alterations and electrical work are disruptive room by room but can normally be phased.
Changeover
The building is without heating during the switch, so the sequence matters. In an occupied building this is usually done outside the heating season or with temporary heat provided.
First heating season
Efficiency depends on how the system is set up and left running. Commissioning should include a return visit during genuine cold weather, and you should ask for that in the contract.
What usually goes wrong or gets missed
Sized to the old boiler
Old boilers were routinely oversized. Copying the rating produces an oversized heat pump that cycles, runs badly and costs more than it needed to.
Import capacity not checked early
The connection cost then arrives late and reframes the whole project.
Efficiency quoted at laboratory conditions
A figure measured at a low flow temperature and mild ambient is not the figure your building will see in January. Ask for a seasonal figure at your design flow temperature.
Fabric work skipped
The pump then runs hot for its whole life, and every year of running cost carries the penalty.
Controls left on the old strategy
Heat pumps want long steady operation. Running one on a boiler style timed on and off strategy wastes much of the efficiency you paid for.
Noise assessed after the location is fixed
Then the unit has to be moved, screened or re specified, all of which cost more than doing the assessment first.
- •It is sized to the old boiler rather than the heat loss, so it runs badly.
- •Import capacity is not checked, and the connection becomes the largest line in the quote.
- •It is sold on a payback that assumed a laboratory efficiency rather than a field one.
- •Fabric work is skipped, so the pump works harder for its whole life.
What to ask an installer
- 01Have you done a room by room heat loss survey, and can I see it?
- 02What flow temperature is the design based on, and what seasonal efficiency does that produce?
- 03What is the seasonal figure at my design conditions, not the laboratory rating?
- 04What electrical capacity does this need, and have you confirmed my site has it?
- 05Which emitters need changing, and is that cost inside this price?
- 06What noise level at the boundary, and has that been assessed against the local limit?
- 07How is hot water handled, and at what temperature?
- 08What is the price of a like for like boiler replacement, so I can compare properly?
- 09Will you return during cold weather to tune the system, and is that included?
- 10What maintenance does this need each year, and what does that cost?
How it interacts with other measures
With insulation
Do the fabric first wherever the programme allows. It reduces the size of the plant, lowers the flow temperature and improves the running cost for the whole life of the system.
With a boiler replacement
These are alternatives and never both. Rule the heat pump in or out before ordering a boiler, because a new boiler closes the option for the life of the plant.
With solar
Solar offsets part of the added electrical load, though heating demand peaks in winter when generation is lowest. It helps the annual position more than the January one.
With EV charging
Both add electrical load to the same connection. Plan the capacity for both together or you will pay for two separate assessments and possibly two upgrades.
With an EPC rating
Replacing fossil heating changes the modelled carbon and energy use, so it can move a band, sometimes substantially.
Does it move an EPC rating
Replacing fossil heating changes the modelled carbon and energy use of a building, so it can move an EPC rating.
Ratings matter most if you let the building. Our guide to MEES and the commercial EPC standard sets out the thresholds, the dates and what to do if a building falls short.
Common questions
Will a heat pump cut my energy bills?
Not reliably in a commercial building. Electricity costs more per unit than gas, so the efficiency has to be high enough to overcome that difference. On a well suited building with low flow temperatures it can. Commercial payback is often twenty years or more, so the case is usually plant replacement, carbon or compliance rather than savings.
When is the right time to consider one?
When the existing heating plant is near the end of its life. At that point you are comparing two things you might buy, rather than comparing a purchase against doing nothing, and the comparison is far more favourable.
Do I need to insulate first?
Wherever you can. Better fabric lowers the flow temperature the building needs, which is what makes a heat pump efficient, and it lets you buy a smaller unit.
Do I need to replace my radiators?
Often yes in older buildings. Radiators sized for a hot boiler are too small to deliver the same heat at a lower flow temperature. That cost should be in the quote from the beginning.
Will my electricity supply cope?
Check before anything else. A heat pump adds load, and if your site is close to its agreed import capacity the reinforcement can cost more than the plant.
Air source or ground source?
Ground source is more efficient and quieter but needs land and significant groundworks. Air source is cheaper to install and far more common on commercial sites, at the cost of efficiency variation with the weather and a noise assessment.
Related reading
Where these figures come from
Show the provenance
- Installed cost: An installer prices this one
- The building, heat loss, emitters and electrical work have to be assessed first.
- Seasonal efficiency: 2.3 to 3.4 units of heat per unit of electricity
- Energy Saving Trust field trial across 742 monitored installations.
The figures on this page are modelled ranges for UK commercial buildings, not a quote for yours. Add your building and we will model it on your own roof, load and rating.