Wales, Scotland and Northern Ireland: how the standards differ

Wales: the same idea, drafted separately

The Building etc. (Amendment) (Wales) Regulations 2026 were made on 3 March 2026. Most of the instrument came into force on 1 July 2026; the renewable generation provisions — regulations 3, 8(1), 8(2) and 8(4) — come into force on 4 March 2027.

The new requirement reads:

L2A.—(1) When a dwelling or a building containing a dwelling is erected, a system for renewable electricity generation must be installed on-site.

(2) The system installed under sub-paragraph (1) must be — (a) designed to enable any electricity generated by it to be available for the use of residents of the buildings, and (b) capable of generating a reasonable output taking into account the design of the buildings and its surroundings.

Anyone who has read England’s L3 will recognise the structure immediately: install a system, make the electricity available to residents, achieve a reasonable output. The exemptions match too — a “relevant building” within regulation 7(4), and a building where a reasonable output is not possible given design or surroundings.

What we do not have is the Welsh sizing method — the equivalent of England’s notional array. It will be in the Welsh Approved Document L (2026), published in April 2026, and gov.wales blocked our access to it. See the note at the foot of this page; we would rather have a hole than a guess.

Scotland: not a requirement, and easy to misread as one

Scotland’s building standards are set under the Building (Scotland) Regulations 2004, with statutory guidance in the Building standards technical handbook: domestic — section 6 on energy and section 7 on sustainability. The current edition was published on 9 March 2026 and applies to warrants submitted on or after 6 April 2026.

Two places photovoltaics appear, and neither is a requirement:

In the sustainability levels. Mandatory standard 7.1 requires a statement of sustainability, with levels from Bronze upwards. The optional Bronze Active and Silver Active levels require a low or zero carbon generating technology — but photovoltaics are one of several qualifying technologies, alongside wind, heat pumps, solar thermal, combined heat and power, fuel cells, biomass and biogas. The mandatory Bronze level does not require any of them.

Inside one compliance calculation. The notional dwelling used to set the target emissions rate under standard 6.1 includes photovoltaics for the fossil-fuel-heated compliance package, at a capacity of 0.01 kWp per square metre of total floor area, capped by roof area. That figure is an order of magnitude smaller than England’s 0.22 kWp/m² — but the comparison is misleading, because the two do completely different jobs. Scotland’s is an assumption inside a model for one heating route. England’s defines a target you must meet.

The direction of travel in Scotland is a general fabric and energy standard — the “Scottish equivalent to the Passivhaus standard” — rather than a solar mandate, with implementation discussed for 2028. Scotland’s New Build Heat Standard, which is sometimes described as a Future Homes Standard equivalent, is a heating measure: it prohibits direct-emission heating systems in new buildings. It has nothing to say about generating electricity.

Northern Ireland: proposed, not adopted

The edition in force is Technical Booklet F1, June 2022 — published 25 March 2022 and effective from 30 June 2022. On renewable electricity it encourages rather than requires:

Where renewable generation technologies are used to produce electricity, designers are encouraged to engage at an early stage with Northern Ireland Electricity Networks (NIE) to confirm that an export connection can be provided.

A Department of Finance discussion document of 2023 proposed, as one option in a phased uplift, a photovoltaic requirement sized at 40% of roof plan area divided by 6.5 — worked in the document as 3.2 kWp for a 104 m² two-storey house — with an alternative option of low-carbon heating instead of PV.

Note how close that is to England’s rule, and how different: 40% of the roof plan area, not of the ground floor area, and a divisor rather than a panel-efficiency multiplier.

We found no adopted outcome, no consultation response, and no new edition of Technical Booklet F1. As far as we can establish, nothing has been enacted.

If you are building, buying or designing across borders

Check which nation’s rules apply, not which nation’s coverage you read. An England Approved Document has no force in Wrexham or Kirkcaldy.

In Wales, the date is 4 March 2027, and the instrument is WSI 2026/60. Get the Welsh Approved Document L (2026) for the sizing method — and if you do, we would be glad of a copy.

In Scotland, do not assume a solar requirement exists. If a developer tells you the house has solar “because of the regulations”, the regulations are not why.

In Northern Ireland, treat any claim that a requirement is coming as a proposal until a new Technical Booklet F1 says otherwise.