Energy-Efficiency Upgrades During a Renovation: Insulation, Glazing and Heating
If you are already opening up walls, floors and roofs, a renovation is the most cost-effective time to improve your home's energy performance. Adding insulation, better windows and efficient heating while the builders are on site avoids paying for access twice. This guide covers the main upgrades, in a sensible order, for London homeowners and landlords. Prices and grants change, so we have kept it general.
Start with the building fabric
The fabric of the house, meaning its roof, walls, floors and windows, determines how much heat you lose. Improve this first, and any heating system you install later can be smaller and work more efficiently.
Roof and loft insulation
Heat rises, so the roof is often the best place to start. Where you are converting a loft, insulation is a requirement of building regulations, and getting the detailing right matters as much as thickness. In unconverted lofts, topping up insulation is generally one of the more affordable improvements.
Walls
Many London homes have solid brick walls, which lose more heat than modern cavity walls. Options include insulating internally during a refit, or externally where the exterior is being worked on, though conservation areas and listed buildings may restrict external changes. Cavity walls, where present, may be suitable for cavity insulation, subject to a survey. Wall insulation affects ventilation and moisture, so get advice before committing.
Floors
If you are lifting floorboards or building an extension, insulating floors can be done relatively easily at the same time. Ground-floor insulation is often tackled as part of garage conversions and extensions.
Windows and doors
Replacing old single-glazed or failing double-glazed units with modern double or triple glazing reduces heat loss and noise. Look at the frame material, the glass specification and the quality of installation, because draughts often come from poorly sealed edges rather than the glass. In conservation areas, check design requirements before changing windows.
Airtightness and ventilation
The tighter you make a house, the more important controlled ventilation becomes. Without it you can trap moisture, and risk damp and mould. Extractor fans, trickle vents and, in some cases, mechanical ventilation help keep air healthy. Building regulations set ventilation requirements for new work, so plan for it from the start.
Heating and hot water
Once the fabric is improved, review your heating. Options include:
A modern high-efficiency boiler with good controls.
Underfloor heating, which suits new floors in extensions and pairs well with lower flow temperatures.
Heat pumps, which work best in well-insulated homes and need suitable space and design.
Smart thermostats and zoned controls.
Solar panels, subject to roof orientation and building constraints.
For heating and renewables, the right choice depends on your property, so ask for specialist design advice. We can coordinate the right specialists as part of a wider project.
Order of work that makes sense
Survey the house and set priorities, such as comfort, running costs or resale.
Fix the fabric: roof, walls, floors, then windows.
Address airtightness and ventilation.
Design the heating system around the improved fabric.
Add controls, lighting and, if suitable, renewables.
Keep records, since certificates and Energy Performance Certificate improvements can be useful when selling or letting.
If you are a landlord, bear in mind minimum energy efficiency requirements for lettings, which change over time. Check the current position with your local council or an adviser.
Keep in mind that insulation and airtightness work best as a system. Adding thick insulation without addressing ventilation or damp risk can create new problems, so ask your builder to explain how each element fits together. In older properties with solid walls, materials that allow moisture to move can be more appropriate than sealing everything tightly.
An Energy Performance Certificate can help you see where the weak points are, and a renovation is a good moment to commission a fresh one. Whether you are staying for decades or letting the property, a more efficient home is easier to sell, cheaper to heat and more comfortable to live in.
If you are unsure where to begin, a short survey of the house, ideally combined with the builder's site visit, is a good first step. It will highlight draughty junctions, thin insulation and ventilation gaps, and give you a sensible list of priorities to fit around your budget and the rest of the project.
Frequently asked questions
Are grants available?
Government and local schemes come and go, with eligibility rules. Check the official sources for what is current.
Will it pay for itself?
Savings vary with the property, energy prices and what you install. Comfort and resale appeal are often as important as bills.
Can I do it in stages?
Yes, but combining insulation with other building work saves disruption. Our refurbishment and extension teams plan this together.
Make your renovation work harder
The cost calculator gives an early idea of overall project costs, and our loft conversion work always includes insulation to current regulations. Contact TNK to discuss what suits your home.
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