The hot topic

Having just experienced the UK’s third heatwave of 2025, we thought it would be timely to look at how homes can be designed to cope with the extremes of Mother Nature and the solutions that can help to mitigate whatever she throws at us.

We Brits love talking about the weather – presumably because topsy turvy weather in this country is nothing new; I guess if you live somewhere where it is constant, then there is not much to say. If we know anything about the weather here, it’s clear that unpredictability is the baseline but, according to recent scientific reports, it is becoming increasingly extreme. By mid-July, we’ve had seemingly back-to-back yellow warnings for flash floods, prolonged extreme temperatures and then drought conditions, with the inevitable hose-pipe bans emerging across the country. Increasingly, we are seeing that the impact of all this is really beginning to shape how our clients are thinking about their homes. For those building or renovating at the upper end of the market, climate resilience is no longer just a technical footnote or a sustainability badge; it’s a growing part of the brief. Clients want to ensure that their home will respond to whatever the weather throws at it.

A home that knows how to stay cool

Summer 2025 has already brought several separate heat spikes over 30°C and the Met Office expects “above-average temperatures to persist” through late August. As UK homes were largely built to retain heat, not shed it, this poses a challenge, especially for large properties with glazed extensions or south-facing gardens.

High-end solutions go far beyond retrofitted air conditioning. Architects and engineers are now designing with a full cooling ecosystem in mind:

Passive ventilation systems use stack effect and cross-breezes to circulate cool air without mechanical input
Brise-soleil, shutters and deep window reveals help reduce solar gain while maintaining clean architectural lines
Phase-change materials and high-thermal-mass stone or clay finishes can store coolness and slowly release it through the day
Discreet air-to-air cooling units, paired with heat pumps, are being used more frequently in bedrooms and upper floors, where heat tends to accumulate

For many clients, comfort now means not just staying warm in winter, but avoiding reliance on artificial cooling in summer.

And when the rain arrives all at once

2025 has also brought sudden and intense rainfall events, particularly across the South and East of England. In mid-May, Norfolk saw over a month’s worth of rain in 24 hours – overwhelming drainage systems and causing widespread property damage.

For property owners, the question is no longer if rain will fall, it’s how quickly it will arrive and where it will go.

Current best practice includes:

Permeable external surfaces, such as resin-bound gravel or permeable stone, to slow runoff
Underground attenuation tanks that hold rainwater and release it gradually into the ground or system
Rain gardens and bioswales that double as landscape features, while filtering and holding excess water
Raised electrical plant rooms, utility cores and floor slabs to protect critical infrastructure from sudden inundation

Even in areas not currently classed as flood-prone, clients are exploring these measures as a way to protect not just property value, but peace of mind.

Heating that’s ready for extremes

Though summers are growing hotter, the UK’s winters are also becoming more erratic, with cold snaps often arriving suddenly after unusually warm periods. The result is a greater strain on heating systems and a push toward more adaptive technologies.

Clients are increasingly investing in:

Air-source and ground-source heat pumps with both heating and cooling functions
Zoned heating systems, allowing parts of the home to warm or cool independently
Solar PV with battery storage, offering backup in the event of grid outages or energy price shocks
Smart control systems that anticipate weather changes and adjust settings before discomfort is felt

While sustainability often drives these decisions, many clients now frame them around resilience – the ability for a home to take care of itself, no matter what happens outside.

Preparing for the unexpected

One of the most common conversations with are now having early on with client teams isn’t about luxury finishes or styling trends (though that is still key of course), it’s about how the home will respond to the environment. If a storm hits during a holiday abroad, will the house protect itself – and alert someone if it doesn’t? Can the bedrooms be ventilated naturally on hot nights? And, will the wine cellar stay cool in a power outage? OK – that does sound a little flippant and ‘First World Issues’, but it does illustrate an important point – if you are storing valuable items at controlled temperatures, then there does need to be a back-up plan. These are no longer niche concerns. They are becoming part of what defines a well-designed, future-facing home.

People’s concerns about climate change and the erratic UK weather generally is changing and the built environment doesn’t have to lag behind. There is now a rich palette of architectural, mechanical and material strategies that allow homes to hold their ground – to stay dry, cool, warm, breathable and ready for anything. It’s all about working smarter, not harder, whilst alleviating pressure on unsustainable, quick fix solutions.

For people building homes that are meant to last generations, the question is no longer whether to prepare, but how best to do it.

Introducing our new offering

We are really delighted this month to be able to tell you about the launch of a new division within Castellum. Joining the three existing teams, London, Country and Cotswolds, is Castellum Studio.

Fast, flexible and focused on excellence

Castellum Studio was created to extend the company’s hallmark quality and attention to detail to a specific market: smaller residential projects, where speed, simplicity and personal service are key.

Our vision is to uphold the highest standards of craftsmanship, on par with every Castellum division, while bringing a more agile and responsive approach to smaller bespoke projects. We aim to be the company that everyone wants to work with – clients, architects, sub-contractors, tradesmen and labourers alike – by creating long-term relationships built on trust, delivery and continuity. This includes growing our workforce organically and becoming a centre of excellence for training the next generation of Castellum site managers and quantity surveyors.

What makes us different?

Castellum Studio will be our in-house ‘problem solver’ – a team capable of tackling complex build details, undefined budgets and fast-moving programmes where traditional sub-contractor models fall short. Our unique strength lies in our permanent workforce, which allows us to:

Take on enabling works, strip-outs, groundworks and structural packages quickly
Provide reliable support to other Castellum divisions
Simplify handovers and reduce snagging
Reduce reliance on sub-contractors, leading to smoother delivery and better client outcomes
Offer fast and cost-effective solutions where adaptability is key
Offer maintenance services and long-term client care

This model gives the whole group greater flexibility and commercial leverage and ensures our clients benefit from fewer trade conflicts, clearer lines of responsibility and consistently high standards across every stage of the build.

Enhanced by design

Castellum Studio also has the ability to partner with the group’s in-house architect team to offer creative design solutions.

Our pledge

We aim to be the customer service face of Castellum – keeping long-lasting relationships with clients and ensuring they always know where to turn when they need support. Fast, flexible and accountable, we’re here to deliver exceptional results with the quality Castellum is known for and with the speed and simplicity our clients hope for.

Please do not hesitate to contact us for more information.

Email :- [email protected]