How to improve home energy efficiency with insulation

Start with how your home actually loses heat

Edinburgh and the Lothians have some of the most characterful housing stock in the UK, and also some of the hardest to keep warm. Sandstone tenements, solid stone villas, rendered 1930s semis and post-war council-built estates all behave differently when the wind comes off the Forth. Before you spend anything, it helps to know where the heat is going.

In an uninsulated home, roughly a quarter of heat escapes through the roof and around a third through the walls. Floors, draughts and windows account for most of the rest. If you live in an exposed spot — Portobello, Musselburgh, the upper slopes of the city or a hillfoot village — wind-driven rain and driving wind make those losses worse, and it also means some insulation materials need more careful detailing than a generic guide would suggest.

The order that usually makes financial sense is: draught-proofing and loft insulation first, then floors, then walls. Loft insulation is cheap, quick and effective. Solid wall insulation is transformative but expensive, so it is best tackled once the simpler measures are done.

Loft insulation: the quickest and cheapest win

If your loft is cold, draughty and has joists you can still see, this is where to start. The current recommendation is around 270mm of mineral wool laid between and across the joists. If there is already 100mm in place, topping it up is straightforward and you will notice the difference on the first frosty morning.

• Never compress insulation to fit — squash it and you lose most of its value.
• Keep the eaves ventilation gaps clear so the roof space can breathe; blocked vents lead to condensation and damp rafters.
• Lag any pipes and the cold water tank while you are up there, and insulate the loft hatch with a rigid board and a draught seal.
• If you have boarded the loft for storage, consider raising the floor so the insulation can stay at full depth.

Homes with rooms in the roof need a different approach — rigid boards fitted between or under the rafters — and that work normally needs a building warrant, so take advice before you start cutting.

Walls: cavity, solid stone and tenement realities

Houses built from the 1920s onwards often have a cavity that can be filled with blown insulation. It is quick, relatively low-cost and usually done from the outside with minimal disruption. It is not always suitable, though. Properties on exposed coastal sites with a history of wind-driven rain penetration may need an assessment first, and in tenements the cavity may run between flats, so the work has to be planned for the whole block rather than one address.

Solid walls are the bigger challenge. Options include:

• Internal insulation — rigid boards or insulated plasterboard fixed to the inside face. You lose roughly 60–100mm of room width per wall and must manage cold bridging at junctions.
• External wall insulation — a rendered or clad system that wraps the outside. Very effective, but it changes the look of the building and needs planning permission or listed building consent in many Edinburgh cases.
• Breathable, natural materials — lime-based and wood-fibre systems suit traditional stone construction well, as they allow moisture to move rather than trapping it.

Getting this wrong risks interstitial condensation inside the wall, which is far more damaging than a slightly cold room. Use an experienced designer and confirm whether a building warrant is required.

Floors: the chill underfoot

Cold floors are often felt before they are seen. In ground-floor flats and houses with suspended timber floors, insulation can be fitted between the joists from below if there is a crawl space, or by lifting floorboards room by room. Mineral wool held in place with netting is the usual approach, and the underfloor ventilation must stay open.

Solid concrete floors can be insulated on top with rigid boards and a new floor finish, though this raises the floor level and affects door heights. Upper flats rarely benefit from floor insulation, but draught-proofing around skirting boards and floorboards still helps.

Draughts, glazing and getting ventilation right

Draught-proofing is inexpensive and often the best value-for-money measure in an older property. Letterboxes, keyholes, sash window margins, chimneys and ill-fitting external doors are the usual culprits.

Be careful with chimneys and any room with an open flue — these need ventilation to work safely and to keep the fabric dry. Blocking everything airtight in a solid-wall tenement flat with washing drying indoors is a recipe for mould. Fit trickle vents, use extract fans in kitchens and bathrooms, and let rooms air briefly each day rather than leaving windows ajar for hours.

Secondary glazing is often the practical choice for sash windows in conservation areas, where full replacement may not be permitted.

Costs, grants and the order to do things

Loft insulation and draught-proofing can often be done for a few hundred pounds. Floor insulation is a mid-range job. Wall insulation is the significant investment, and external wall work on a tenement needs agreement from every owner plus a factor's involvement.

Before committing, get an Energy Performance Certificate, ask about government-backed grant and loan schemes, and use installers who are certified for the specific measure. Co-ordinating with neighbours in a tenement block usually reduces cost per flat and improves the result for everyone. Do the simple things first, then work upwards — your bills, your comfort and the building itself will all benefit.