Why Refurbished Homes Need Air Conditioning in 2026

Updated: June 2026

Following the record-breaking June 2026 heatwave, we’ve updated this guide with observations from homeowners, our refurbishment projects, and the lessons reinforced by the hottest June on record.

Over the past few years, I’ve noticed one conversation coming up more and more during house refurbishments and extensions across London: air conditioning.

Many homeowners initially tell me the same thing:

“We don’t really need AC in London. There are only a few hot days each year.”

And honestly, I completely understand why people think that way. Most clients are comparing their future refurbished home to the older Victorian property they currently live in — often a house that feels relatively manageable during summer despite having no cooling system at all.

But what I try to explain is that the comparison is not really 1-to-1 anymore.

Older houses were naturally far less insulated and much less airtight. They had draughts around windows, suspended timber floors, older roof structures, chimneys, and plenty of natural air leakage throughout the building. While inefficient in winter, those homes also released heat much more easily during warmer months.

Modern refurbishments completely change how a property behaves.

Today, most full refurbishments include:

• high-performance insulation
• modern glazing
• airtight construction methods
• larger bifold or sliding doors
• rooflights and skylights
• open-plan extensions

The result is a far more comfortable and energy-efficient home during winter — but also a home that can retain heat very aggressively during summer.

I’ve had quite a few clients come back after completion saying:

“If we knew the house would get this warm, we would have looked at AC differently.”

That’s one of the main reasons I wanted to write this article — not to push air conditioning, but to help homeowners understand how modern refurbishments are changing the way homes perform.

When we first published this guide, some homeowners still questioned whether air conditioning was becoming necessary in London.

Just weeks later, the June 2026 heatwave provided the answer.

For many homeowners, it was the first real test of how their refurbished home performed during extreme summer temperatures.

The UK experienced its hottest June on record, with temperatures exceeding previous June records on three consecutive days. Many refurbished homes with modern insulation, large glazing and open-plan layouts became difficult to keep comfortable, especially in loft bedrooms and upper floors.

During the heatwave, several previous clients contacted us—not because something had gone wrong, but simply to say thank you. They told us the air conditioning we had recommended during their refurbishment made their homes genuinely comfortable throughout the hottest days. Meanwhile, many homeowners elsewhere only began looking into cooling solutions after the heat had already arrived.

That is exactly why we wrote this guide: not to sell air conditioning, but to help homeowners make informed decisions while they are still renovating, when installing a system is considerably easier and more cost-effective.

In many ways, modern refurbishment standards are victims of their own success.

We work very hard to create homes that are:

• well insulated
• energy efficient
• airtight
• comfortable during winter

But when you combine those standards with:

• large glazing systems
• south-facing extensions
• rooflights
• open-plan spaces
• warmer London summers

you create a house that can also trap heat extremely effectively.

This is especially noticeable in:

• rear kitchen extensions
• loft conversions
• top-floor bedrooms
• homes with large sliding doors
• heavily glazed open-plan areas

Years ago, overheating was not something many London homeowners thought about seriously. Today, I believe it’s becoming a genuine design consideration during major refurbishments.

Another important factor I often explain to homeowners is ventilation.

Older Victorian and period houses were never truly airtight buildings. They naturally ventilated themselves through:

• original chimneys
• suspended timber floors
• older roof structures
• draughty windows and doors
• gaps within the building fabric

Many older London homes also had multiple functioning chimneys which constantly moved air through the property, even when not actively used.

During modern refurbishments, these natural ventilation paths are often removed or significantly reduced. Chimneys are closed, buildings become heavily insulated, windows become airtight, and construction standards improve dramatically.

At the same time, most residential refurbishments in London still do not include full mechanical ventilation or HVAC systems designed to actively manage airflow and indoor temperature.

As a result, modern homes often retain both heat and humidity much more aggressively than older properties ever did.

This is one of the biggest reasons why many homeowners are surprised by how differently a fully refurbished house behaves during summer compared to the original building they lived in before works started.

Additional issue I increasingly see in modern refurbishments is the misunderstanding around ventilation.

Many homeowners assume that modern airtight windows with trickle vents automatically provide sufficient ventilation for the entire property. In reality, trickle vents alone often provide only very limited background airflow and are not designed to replace a properly considered ventilation strategy.

Older houses naturally ventilated themselves through chimneys, draughts, suspended floors, and gaps throughout the building fabric. During refurbishment works, many of these natural airflow paths are removed completely. Chimneys are sealed, insulation is upgraded, and modern windows dramatically reduce uncontrolled air leakage.

At the same time, most residential refurbishments in London still do not include full mechanical ventilation or HVAC systems designed to actively manage airflow, humidity, and indoor temperature.

As homes become more airtight, managing moisture and airflow becomes increasingly important. Without adequate ventilation, humidity can build up inside the property, which in some cases may contribute to condensation and mould issues — particularly around colder bridging areas, poorly ventilated rooms, or heavily occupied spaces.

This is one of the reasons why overheating, humidity, and indoor comfort are becoming much bigger considerations in modern refurbishments than they were in older period homes.

One of the biggest mistakes I see is homeowners treating air conditioning as something that can always be added easily later.

Technically, yes — it usually can be retrofitted.
But practically, it often becomes much more difficult and expensive once the refurbishment is complete.

Proper AC installation require:

• pipework routes (and pipes sizes are dependable on unit type and size)
• drainage (lots of units require pumps to help them where gravity drain is not possible)
• electrical wiring (this is based again on unit size)
• condenser locations (this is where all pipe work start and finish)
• ceiling voids (for running pipes or concealed ductings)
• boxed bulkheads
• wall and ceiling access

Once decorating, joinery, flooring, and finishes are complete, retrofitting becomes far more disruptive.

This is why I always encourage clients to at least think about future cooling requirements during refurbishment works — even if they choose not to install a full system immediately.

Planning early gives homeowners far more flexibility later.

Another misconception I hear regularly is:

“We don’t want AC everywhere.”

And that’s absolutely fine.

Modern air conditioning systems are extremely flexible.

Some homeowners only cool:

• the kitchen extension
• loft bedrooms
• the top floor
• a home office
• master bedroom suites

Others prefer multi-zone systems or full-house concealed solutions.

Every property is different, and every family uses their home differently. Air conditioning does not have to mean turning the house into a commercial building. Sometimes a single well-designed area can completely change comfort levels during summer.

In many Southern European countries, cooling only the main living areas is already a very common and practical approach. Rather than installing large whole-house systems, many homeowners focus on the rooms the family uses most during summer — typically kitchen, dining, and living spaces or primary bedrooms.

This approach is often driven by both practicality and running costs, allowing homeowners to improve comfort significantly without unnecessarily cooling unused parts of the property.

I increasingly see London homeowners adopting a very similar mindset, especially in refurbished Victorian houses where targeted cooling solutions can deliver excellent comfort while remaining cost-effective.

A lot of homeowners still imagine air conditioning as a large white plastic unit fixed high on the wall.

While wall-mounted systems remain common and practical, there are also much more discreet options available today.

Concealed ducted systems can hide almost everything within ceilings or service voids, leaving only slim grilles visible within the room.

However, concealed systems require space, which can become difficult in smaller London properties and Victorian terraces.

Very often, installing concealed AC later means:

• removing ceilings
• opening walls
• lowering ceiling heights
• creating additional bulkheads

This is another reason why early planning matters so much during refurbishment projects.

The earlier cooling is considered, the cleaner and more integrated the final solution usually becomes.

This is probably one of the most common concerns homeowners raise.

And to be fair, older AC systems from years ago were significantly less efficient than modern systems available today.

Modern inverter-driven units are much smarter, quieter, and more energy efficient.

Actual energy usage depends on:

• insulation quality
• glazing performance
• system sizing
• thermostat settings
• zoning
• how the home is used

A properly insulated house with a correctly sized modern system can often perform much more efficiently than people expect.

Like many technologies, air conditioning has evolved enormously over the last decade.

One thing many homeowners don’t realise is that air conditioning should never be selected based only on room size.

Proper system design depends on:

• glazing area
• ceiling height
• orientation
• insulation levels
• solar gain
• room usage

Oversized systems can become inefficient and uncomfortable, while undersized systems may struggle during hotter periods.

Correct calculations are extremely important to achieve the right balance between comfort, efficiency, and operating costs.

In London, air conditioning installation can sometimes involve planning considerations as well.

This is especially important for:

• terrace houses
• conservation areas
• flats
• densely built streets

External condensers may require careful positioning, and in some situations noise assessments may also become necessary.

This is another reason why I believe cooling strategies should be discussed as part of the wider refurbishment process rather than treated as a last-minute addition.

Costs vary significantly depending on:

• the size of the property
• number of rooms
• system type
• accessibility
• installation complexity

A single-room system is obviously very different from a concealed multi-zone installation or whole-house setup.

However, what I often explain to homeowners is that integrating infrastructure during refurbishment is usually far more cost-effective than retrofitting everything later after decoration and finishes are complete.

As a very general guide, basic single-room air conditioning systems in London often start from around £3,000+, while larger multi-zone or concealed systems can increase significantly depending on the size of the property, installation complexity, and specification.

Another thing many homeowners are surprised by is that modern AC systems do far more than simply cool rooms.

Depending on the system, they can also:

• provide heating
• reduce humidity
• improve airflow
• filter airborne particles
• improve comfort during winter and transitional seasons

This can be particularly useful in loft conversions, bedrooms, and highly insulated modern spaces where airflow naturally becomes more limited.