We Welcome the Government’s Warm Homes Plan – But Insulation Quality Must Not Be an Afterthought

We welcome the Government’s £15 billion Warm Homes Plan to upgrade up to five million homes, reduce long-term energy bills, and lift up to one million families out of fuel poverty by 2030.

It is a significant and much-needed commitment. However, we believe the success of the programme will hinge on one crucial factor: the quality of the retrofit work delivered – particularly in the areas most prone to heat loss, damp, and mould.

A Welcome Focus on Home Upgrades

The Government has highlighted home upgrades as one of the most effective ways to cut bills “for good.” We agree. Improving insulation remains one of the simplest and most impactful measures for enhancing energy efficiency and comfort, and creating warm homes.

However, insulation installations have fallen by more than 90% between 2010 and 2024. That dramatic slowdown has left millions of households exposed to cold living conditions, persistent damp, and rising heating costs. The renewed national focus is therefore both timely and essential.

But history shows that funding alone is not enough.

What can the Warm Homes Plan Learn from Previous Schemes?

Dr Alex Boote, Product & Innovation Manager at ARC Building Solutions, emphasises that while investment is critical, it must be matched by high standards of workmanship.

“The Government’s investment is essential, but retrofit history tells us that funding must be matched by quality delivery,” says Dr Alex. “We’ve all seen the headlines about what happens when insulation is installed poorly.”

Independent audits of previous programmes, including the Energy Company Obligation (ECO) Schemes, revealed widespread performance failures. In some cases, insulation increased heat loss rather than reducing it, trapped moisture within the building fabric, and significantly raised the risk of damp and mould.

Audit findings included:

• 98% of external wall insulation audits identifying major defects
• 29% of internal wall insulation audits finding significant issues

Some installations posed immediate risks to occupant health and safety. These outcomes highlight how critical proper design and workmanship are to achieving the intended performance.

The Overlooked Risk at the Eaves

If we want warmer, healthier homes, the details matter – especially at junctions.

One of the most frequently neglected areas in retrofit projects is the eaves, where the roof meets the external wall. This junction is a common source of thermal bridging and one of the leading contributors to post-retrofit mould growth.

Even when eaves insulation is attempted, ventilation is often obstructed or omitted entirely. This can make condensation and moisture problems significantly worse.

“Neglecting the eaves can undo the benefits of everything else,” Dr Alex explains. “You can insulate most of the home perfectly, but if the eaves are left untreated, warm, moist air gets pushed towards one of the coldest parts of the building, creating condensation – which is why damp and mould often appear after retrofit, and not before.”

Getting Retrofit Right

“Our retrofit range was developed specifically to tackle this issue,” says Dr Alex, “boosting thermal performance while preserving essential ventilation airflow. You can’t deliver a ‘warm home’ if the insulation strategy creates new damp risks elsewhere.”

As the Warm Homes Plan moves from policy to practice, we believe the industry has a responsibility to ensure that lessons from previous schemes are not repeated.

The focus must now be on delivering retrofit solutions that are not only designed to perform as intended, but installed correctly to ensure lasting improvements in comfort, health, and building durability.

The ambition is welcome. The investment is vital.