Energy retrofits are pushing rebuild costs up, is your cover enough?

Energy-efficiency upgrades are good news for comfort, bills, and long-term sustainability. But there is a less obvious side effect that many property owners are only just starting to notice: retrofits can push rebuild costs higher, sometimes significantly. If your insurance sum insured has not been reviewed recently, you could be carrying a shortfall without realising it.

This matters because UK property owners are already dealing with a widespread underinsurance problem. Recent industry reporting suggests most buildings are insured below their true rebuild cost, and that retrofit work such as insulation, heat pumps, solar panels, and more specialist materials can make the gap even wider. The key question is no longer just whether your home or building is insured, but whether it is insured for what it would actually cost to rebuild today.

Why retrofit work changes rebuild values

Retrofits do more than improve energy performance. They can alter the construction of a building, the specification of materials, the labour needed to replace them, and the rules that apply if a property is damaged and has to be rebuilt. That means the rebuild figure can move well beyond what a basic historic insurance estimate might suggest.

According to a July 30, 2025 Insurance Business report, energy-efficiency upgrades are raising reinstatement costs, while many owners are not updating sums insured. RebuildCostAssessment’s Sharon Masters warned that if the insurance cover stays the same, the risk of underinsurance increases. In simple terms, the building may be worth more to rebuild after the work than it was before.

Even a retrofit costing around £50,000 can materially alter the rebuild value, and more extensive upgrades can exceed £60,000 because of specialist labour and materials. Those changes do not always show up in a market value estimate, which is one reason insurance reviews are so important after major works.

How underinsurance can affect a claim

When a property is insured for less than its true rebuild cost, the financial impact may not become clear until after a claim. That is when the Average Clause can apply, meaning the insurer may reduce the payout proportionally if the sum insured is too low. The result can be a much smaller settlement than the policyholder expected.

For example, if a property’s true rebuild cost is much higher than the figure on the policy, a partial claim can still be reduced in line with the level of underinsurance. That can leave owners needing to fund essential repairs themselves, which is often difficult at the very moment when they are already dealing with disruption and stress.

This risk is not theoretical. RebuildCostAssessment says 76% of UK buildings are underinsured, with only 4% insured for the correct amount. On average, properties are covered for around 60% to 65% of true rebuild cost, which suggests many policyholders may be exposed without knowing it.

Retrofits can make rebuild cost higher than market value

One of the most important points for homeowners and landlords to understand is that rebuild cost and market value are not the same thing. A property can have a market value based on location, demand, and land value, while the rebuild cost reflects the expense of reinstating the structure, materials, fittings, and compliance requirements after a loss.

After retrofit work, the rebuild cost can rise enough to exceed market value. Insurance Business reported cases where the cost of rebuilding a retrofitted property was higher than the property’s market value, increasing the chance of a shortfall after a fire, flood, or other insured event. That is why using market value as a proxy for cover can be misleading.

This is especially relevant where the retrofit involves systems such as heat pumps, improved insulation, solar panels, or upgraded windows and roofing. These features can introduce specialist installation, bespoke components, and a more complex replacement process, all of which can increase reinstatement costs in a claim scenario.

The wider UK risk picture remains concerning

The problem is not limited to homes that have recently been upgraded. A January 5, 2026 Insurance Business report said 70% of UK properties were insured below true rebuild cost in 2025, and that cover averaged just 66% of what was required for a full rebuild. That suggests underinsurance is still widespread across the market.

The same report also noted that 71% of brokers in 2025 reported more claims being reduced because of underinsurance. That is a strong sign that policyholders are increasingly discovering the gap only after a loss has happened, rather than at renewal or during a routine review.

With energy-efficiency requirements and rising energy costs driving more retrofit activity, the rebuilding landscape is changing quickly. RebuildCostAssessment also pointed to Scotland’s proposed Heat in Buildings Bill, which would require landlords to meet minimum energy standards by 2028 and owner-occupiers by 2033, showing how regulation is accelerating the trend.

What property owners should do now

The most practical step is to reassess your rebuild cost whenever you carry out significant works, and certainly after any retrofit that changes the building’s structure or specification. It is not enough to rely on an old figure carried forward year after year, especially when labour and material costs have moved on.

Professional rebuild-cost assessments are preferable to using market value or a rough estimate. RebuildCostAssessment recommends that insurers and brokers review sums insured after upgrades and use professional assessments rather than assumptions. That approach can help ensure your policy reflects the real cost of reinstatement if the worst happens.

It is also sensible to check whether your policy includes cover for code-related upgrades. Older guidance from Triple-I notes that Ordinance or Law coverage can help pay for compliance-driven changes during a rebuild, which becomes more relevant when retrofit work or changing regulations increase the cost of meeting current standards.

How to review your cover without overcomplicating it

If you have made changes to your property in the last few years, start with a simple checklist. Have you added insulation, solar panels, a heat pump, double or triple glazing, a new roof, or upgraded electrics and plumbing? If so, your rebuild cost may have changed even if the property still looks similar from the outside.

Next, compare the insured amount on your policy with an up-to-date rebuild estimate. If the numbers are close, that is reassuring. If there is a large gap, the policy should be reviewed as soon as possible. The goal is not to chase a perfect figure every time, but to avoid a clearly outdated sum insured.

If you are unsure, ask a qualified broker or insurance professional to explain how the figure was set and whether it reflects recent retrofits. A short review now can help reduce the risk of a much bigger problem later, especially given how common underinsurance appears to be across the UK market.

Why this matters for household budgeting

Insurance affordability is also part of the conversation. In 2026, home insurance costs remain under pressure in several markets, and rising rebuild and replacement costs can feed through into premiums. That can make it tempting to trim cover to save money, but doing so may increase the risk of an expensive shortfall after a claim.

Recent US reporting has linked rising rebuild costs to underinsurance risk, with Insurance Business noting that homeowners may be underinsured if cover has not kept pace with repair or replacement costs. While the figures are not the same as in the UK, the principle is familiar: if reinstatement costs rise, cover needs to keep up.

For UK residents, the takeaway is straightforward. A slightly lower premium is unlikely to be helpful if the sum insured is too low when a major claim happens. The better approach is to balance affordability with a realistic rebuild figure, especially after energy-efficiency improvements.

Retrofitting is a sensible long-term investment in your property, but it should be matched by a fresh look at your protection. If your building has changed, your cover should change too. A quick review now could make a significant difference later.

In uncertain times, the aim is reassurance rather than guesswork. Checking your rebuild cost, understanding the impact of retrofit work, and making sure your policy reflects current realities are practical steps that can help protect your home or investment. If you have not reviewed your cover recently, now is a good time to do it.