SAP calculations in Enfield

Heritage in Enfield: conservation areas and listed entries

Enfield has 24 conservation areas and Historic England lists 301 entries, among them 22 at Grade II*. Heritage at Risk entries number 22.

Old farmhouses and country-edge cottages are the awkward cases. Solid walls cannot take a cavity fill, and the listed ones may not accept new external insulation at all. Approved Document L treats listed and traditional buildings as special cases, where the aim is to improve energy performance as far as is reasonably practicable; we record the reasoning so the assessor and the officer read the same note.

Detached homes, terraces and what each needs

Around 61.2 per cent of Enfield households live in a house, and 52.4 per cent own it. A detached house sold for roughly £1,243,138 on average, against £496,816 for a terrace, so the same energy rule lands on very different budgets.

For a terrace the answer is nearly always simple limits and a clean specification. For a detached house with a wide glazed gable, we usually run the trade route and balance glass against a better roof and floor.

The limits a new element has to meet

The guidance for new elements in an existing dwelling says: New elements in existing dwellings, limiting U-values W/(m²·K): roof 0.15, wall 0.18, floor 0.18, windows 1.4 (or WER Band B), doors 1.4. A thick insulation layer on a flat-roofed addition is the usual cost of meeting the roof figure.

Glazing is capped on the simple route: 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. If your plan breaks it, the alternative is on the table: Alternative routes: area-weighted U-value (para 10.9) or a SAP calculation against a notional extension (para 10.10).

We build that check into the loft conversion drawings and the rear-addition sets alike, since a rooflight is glazing for this purpose just as a door is.

Overheating and the EPC on a new Enfield build

A new home faces a second test. Approved Document O (overheating) applies to new residential buildings. A south-facing glazed room on an Enfield plot with no street shade needs a view on shading and opening sashes, which the assessor reads from the elevations.

Afterwards comes the certificate: An energy performance certificate is required on construction of a new dwelling. We keep the specification on the sheets so site substitutions do not quietly lower the rating.

Building for the long term on an Enfield plot

Many Enfield owners stay in their homes for decades, and a rural-edge house is expensive to heat if it is badly insulated. A SAP calculation is a prediction of running cost as well as a compliance document, so it is worth reading for that alone.

We show the effect of options in plain terms: what an extra layer in the roof does, what a better window does, what a heat pump does. The lead figure is the same score building control sees, and the supporting figures help you decide where to spend.

If the house is a replacement dwelling, we also coordinate the energy specification with the structural design early, since thick walls and deep insulation alter the foundations and the roof structure. Raising that after the engineer has finished is how a simple change becomes a redraw.

Before ordering windows, send us the supplier datasheet. A declared performance figure from the manufacturer is what the assessor wants, and it often beats the default value, which can move a borderline design onto the simple route.

Working with the rest of your Enfield drawings

See the planning view under architectural drawings in Enfield and the construction view under building regulations drawings in Enfield. For a rear addition, our rear extension drawings in Enfield show the build-up the assessor will use.

The energy work is a fixed quote after a free constraints check, VAT included. Tell us the address and whether the house sits near the Green Belt, and we confirm the route.