The Future Homes Standard package: heat pump plus solar

Two separate requirements, one result

It is worth keeping these apart, because they are often described as one thing.

The energy and carbon targets — requirement L1 and the associated calculations — set what the dwelling as a whole must achieve. They do not name a technology.

Requirement L3 — the renewable generation rule — is a separate, new requirement, and it is about generation rather than heating.

A developer could in principle meet the targets some other way, and could meet L3 with a technology other than photovoltaics: Approved Document L says on-site renewable electricity “can be generated by photovoltaic panels, or another renewable technology”, with equivalent output. On a house, nothing else is close.

The seasonal mismatch, stated plainly

This is the honest heart of the page.

A heat pump’s demand peaks in winter. Solar generation collapses in winter. Our own seasonal data shows December output at a small fraction of June’s for every UK location we model.

So the picture across a year is:

• Summer — the panels generate far more than the house needs for heating, because it needs almost none. Surplus goes to hot water, to appliances, to an EV if there is one, or is exported.
• Winter — the heat pump draws hard and the panels contribute little.

No amount of battery capacity bridges that, because it is a seasonal gap rather than a daily one. A battery shifts hours; it does not shift months.

Where the honest doubt sits

The government’s own impact assessment does not oversell this, and neither will we:

Despite improvements to energy efficiency relative to the counterfactual, there may be cases where individual household bill savings are small or negative on a per dwelling basis.

The reason given is that most homes in the counterfactual have a gas boiler, and electricity costs several times more per unit than gas. Against a typical existing home, the assessment says annual fuel savings “would be considerably higher”.

So: better than the housing stock, not necessarily better than a brand-new gas-heated house would have been at today’s relative prices. That is a defensible policy position — the point is decarbonisation, and relative prices are a policy variable too — but it is not the same as “cheaper to run”, and buyers should hear the difference.

Heat pump certification, and the paperwork you should get

Approved Document L is specific about this, and it produces a document you should hold.

Two routes only. Heat pump installation work must be certified either by self-certification by a registered competent person, or by certification by a building control body.

Where the installer self-certifies, they or their registration body must, within 30 days of the work being completed, give a copy of the Building Regulations compliance certificate to the occupier and give the certificate or its information to the building control authority.

That certificate is yours. Ask for it, alongside the solar paperwork listed in buying a new build. It will matter when you sell.

The guidance also requires the installation to be inspected and tested against specified standards — pipework and storage heat losses limited, the system appropriately sized, hot water storage appropriately sized, adequate controls, and the system requirements met. Sizing is the one to ask about, because an oversized heat pump cycles and an undersized one disappoints, and neither is visible from the hallway.

Siting, and why it shows up in the design

Two provisions worth knowing if you are looking at plans:

• refrigerant pipework in dwellings should be fully insulated
• heat pumps serving individual dwellings should be located as close to the dwelling as practical, to minimise pipework length

Both are efficiency measures, and both have visible consequences for where the unit ends up — which is a question worth asking before you buy the plot with the narrow side return.

What to do with all this as a buyer

1. Ask for both certificates — the heat pump’s Building Regulations compliance certificate and the solar MCS certificate.
2. Ask what the array is in kWp, and check it against the 40% formula.
3. Ask whether the house is battery-ready, since nothing requires it and retrofitting is dearer.
4. Ask about the heating design, particularly sizing and controls.
5. Do not assume the bill will be lower than a gas home. Assume it will be different, and read the two documents that say so.