SAP calculations in Richmond upon Thames

A borough defined by protected places

Richmond has 85 conservation areas, 819 list entries and 40 Grade I buildings, with 16 registered parks and gardens. 17 entries are on the Heritage at Risk Register.

For the energy design this has a plain meaning. Windows and walls on a protected house cannot always be altered to modern values, and Approved Document L gives historic buildings special consideration. A SAP calculation lets us show how much the rest of the building must do. That is better than guessing, and it makes a consent application easier to explain. Where listed building consent is needed, the calculation becomes part of the argument that the work is proportionate, and the officer sees the numbers instead of an assertion. We say at the quote stage if we think a scheme will need that consent, so the cost and timing are not a surprise.

Large houses, large extensions

59.8 per cent of households live in a house and 62.4 per cent are owner-occupied. The average home sold for £803,249, a detached house for £1,814,548 and a terraced house for £915,886. Extensions on this scale often include large areas of glass.

The rule on glazing states: Windows, roof windows, rooflights and doors in an extension should not exceed 25% of the extension floor area plus the area of openings removed or covered. A large glazed rear wall can break it, and then the document points to: Alternative routes: area-weighted U-value (para 10.9) or a SAP calculation against a notional extension (para 10.10). A calculation is how a large glass extension passes without being downsized. The trade is usually a better roof, floor or wall build-up in exchange for the extra glass, and the numbers show whether the trade works before any money is spent on drawings or on the building itself. If it does not work, we can say so at that point and suggest the smallest change to the design that would.

Prior approval works better here

The council's figures for larger home extensions under prior approval stand out. It granted 78 and refused 30 in the latest year, so grants outnumbered refusals. Those are council-wide figures, not a forecast for a given street.

It decided 1,302 householder applications, granting 83.3 per cent and deciding 98.3 per cent in time. The lawful development certificate service in Richmond upon Thames deals with the planning side of a permitted scheme.

New homes and the timetable

A new dwelling follows the dwelling method: For new dwellings AD L 2026 names two methods: the Home Energy Model (HEM) and SAP; validity dates are in the Notice of Approval. The standard changes on a date: AD L 2026 takes effect 24 Mar 2027 (24 Sep 2027 for higher-risk building work). An energy performance certificate is needed on completion: An energy performance certificate is required on construction of a new dwelling.

Our new build drawings in Richmond upon Thames and building regulations drawings in Richmond upon Thames carry the specification that the calculation assumes.

Nearby and overview

The whole borough is on architectural drawings in Richmond upon Thames. Neighbouring pages are SAP calculations in Hounslow and SAP calculations in Kingston upon Thames.