Here's a straightforward comparison for a standard semi-detached home in the UK:
| Insulation Type | Installation Cost | Annual Saving | Payback Period | 10-Year Net Benefit |
|---|---|---|---|---|
| Foil Insulation | £400 | £200/yr | 2 years | £1,600 |
| Fibreglass Loft | £400 | £150/yr | 2.7 years | £1,100 |
| Cavity Wall | £600 | £200/yr | 3 years | £1,400 |
↔️ Swipe to see more
💡 The compounding effect: These numbers use current energy prices. If energy prices rise (as they have historically over the long term), the real-world return on insulation investment increases proportionally.
The financial case for insulation is compelling, but the full picture includes comfort and health benefits that don't appear in the savings calculations. A well-insulated home maintains more consistent temperatures, eliminates cold draughts, reduces condensation risk, and — for households with elderly residents or young children — can have real health implications.
Cold homes are linked to respiratory problems, cardiovascular disease, and mental health challenges. The NHS estimates that cold homes cost the health service hundreds of millions of pounds per year in preventable illness. Insulation is a public health intervention as much as an energy efficiency one.
There are a small number of scenarios where the standard insulation calculus doesn't apply:
If you're selling imminently — the upfront cost may not be recouped before sale, though energy efficiency improvements generally increase property value and EPC ratings.
Spray foam specifically — due to mortgage risks and removal costs, spray foam can actively reduce property value. This is the one case where insulation may not be worth it. See our spray foam risks guide.
If major building works are planned — if you're planning a loft conversion or roof replacement, it may make sense to combine insulation with those works to avoid installing and then disturbing it.
Use our free 30-second comparison tool to get personalised savings estimates and a matched installer quote.
Check My Home Now →With energy bills elevated and ECO4 funding still available, insulation delivers some of the best returns of any home improvement. Here’s the honest analysis.