Energy Saving Upgrades for Portsmouth Homes: 2026 Guide

Portsmouth has some of the oldest housing stock on the south coast. Walk through Southsea, Fratton or North End and most of what you'll see is Victorian and Edwardian terracing: solid brick walls, suspended timber floors, and wiring that's often decades past its best. Lovely houses. Expensive ones to heat.

We work across Hampshire and Dorset, and more of our Portsmouth enquiries each year are about energy: heating that costs less to run, electrics that can cope with modern demand, and upgrades folded into wider renovation work. Here's where we'd put your money in 2026, with realistic local costs.

Sort the fuse board before anything else

It's not the glamorous end of the job, but nearly every upgrade on this list leans on your consumer unit. Underfloor heating, smart controls, an EV charger down the line: they all need a board with capacity and proper RCD protection, and plenty of older Portsmouth terraces are still running boards that predate all of it.

For a typical three-bed terrace we'd price a modern RCBO consumer unit swap at £600 to £800, which covers testing every existing circuit, the new board, labelling and your electrical installation certificate. Larger homes with more circuits or outbuildings can run to £1,400 or so. It's normally done in a day, and the boards we fit now come with surge protection as standard, which matters given how much electronics a modern household runs. If testing turns up a problem elsewhere in the wiring, we'll show you before we touch it. We always survey before quoting for exactly that reason.

Electric underfloor heating, where it earns its keep

We'll be straight with you: heating a whole house on electric underfloor heating rarely stacks up on running costs, and we say so when asked. Bathrooms and small kitchens are a different story. The mats warm a tiled floor quickly, you run them on a timer for an hour or two a day, and the radiator that used to eat half the wall can go.

As part of a bathroom refit in Portsmouth you're looking at £70 to £110 per square metre installed, including the mat, insulation board and a programmable thermostat. Small rooms sit at the top of that range because the fixed costs don't shrink with the floor. A bathroom's worth of mat goes down in a morning; it's the tiling that sets the pace, not the heating. Our plumbing, heating and electrical team fits these alongside full bathroom renovations, which is by far the cheapest time to do it, since the floor's already up.

Smart heating controls are the cheapest win here

A fitted smart thermostat comes in at £250 to £390 depending on the brand and how your boiler's wired, and it's the one upgrade on this list that starts paying back the same week. Solid-walled terraces hold heat differently to modern builds, so a system that learns the house and runs rooms on separate schedules genuinely earns its money in a Southsea terrace. If you're out all day, not heating an empty house is worth more than any gadget; the thermostat just does it without you having to think about it.

We fit these as standalone jobs, or as part of the smart home, CCTV and Wi-Fi installs we're doing more and more of across Hampshire.

Where older Portsmouth homes actually lose heat

The honest answer: through the fabric. Solid brick walls, uninsulated suspended floors, tired lofts and gappy original sashes will undo a lot of what a clever thermostat saves. We've deliberately not put standalone prices on insulation here because the right answer varies so much house to house. Wall build-up, access, condensation risk and how close you are to the seafront all move the number. We've seen it on jobs around Eastney and Milton: two identical-looking terraces a street apart can need completely different approaches once you open the floors up.

What we will say is that the cheapest time to insulate is when the house is already open. If you're planning an extension or a full renovation, that's the moment to do floors, walls and airtightness properly, and we design it into the job from the first site visit.

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Start with a survey, not a guess

Every house in this city is different, and a quote given over the phone is a guess. If you're weighing up any of the above, book a free site survey with Complete Builds and we'll walk the house with you, test what's there and give you numbers you can actually plan around.