BS 7671 Amendment 4 has been in force for three weeks. The rules are clear: lofts, bedrooms, escape routes and basements without external access are out; outdoor units must sit at least 1 metre from doors, windows and vents.

Reading the text isn't the hard part. Applying it to a specific address is. Three friction points are showing up in practice.

FRICTION 1 — Fewer compliant locations than expected
A typical British terraced house offers a loft (now excluded), bedrooms (excluded), stairways and hallways (excluded), a basement with external access (usable), a garage (usable), and an external wall (usable but constrained by the 1-metre rule). Many older terraces have no garage and no usable basement — leaving external wall as the only option, which then has to satisfy clearance, weather protection and enclosure requirements. Location isn't a choice; it's a countdown.

FRICTION 2 — How the metre is measured
Three things need clarity on site: where the measurement starts (unit edge, or enclosure?), where it ends (window frame, or opening?), and what counts as a vent. This isn't a technical question — it's a process question. Without a shared measurement convention and an escalation path, the same wall produces different verdicts from different installers.

FRICTION 3 — Retrofits and expansions
The rules bind new installations; existing systems aren't required to be modified. But expansions and second battery units count as new installations. The conflict is real: an existing unit may sit in a loft or bedroom, so adding capacity means relocating, re-routing cabling — potentially redoing the whole design. Retrofits become harder than new builds, because you're redesigning inside constrained conditions.

WHAT TO DO
Turn location assessment into a tool — a dwelling diagram, explicit decision rules, an escalation route. Redefine outdoor install kits around the 1-metre constraint: brackets, cable lengths, enclosures, clearance marking. And separate retrofit projects from new builds, assessing existing-location compliance before discussing capacity or price.

TO BE CONFIRMED (official text governs)
Measurement conventions for the 1-metre rule; the exact scope of "expansion" versus "replacement"; whether third-party verification is required under PAS 63100:2024. We make no interpretive claims here.

Sources: Smart Solar Homes; Virtual College installer guidance; Cool Power Co (Oct 2026).

#EnergyStorage #HomeBattery #UK #BS7671 #ResidentialESS

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