Climate change impacts so many things, not least of all your home. What may once have been a warm and cosy sanctuary, perfect for tackling British winters, may suddenly have seemed stifling in one of the hottest summers on record.
Of course, while knocking down your house and starting again isn't an option for everyone (there's a reason why portable air con units sold out so quickly this year), new self-build homes do have the opportunity to tackle the issue head on.
But what could a home built to prevent overheating in the future actually look like? We may not have a consistently blue Santorini-like sky to carry off whitewashed villas, but is it fair to assume architecture will have to change? We posed the question to architect, David Nossiter.
How will a home's structure and roofs develop?
When asked if the traditional British house will become a thing of the past, my answer is no, not in the foreseeable future. It's unlikely that the future of British housing will be defined by a single architectural style. Much of our housing stock is over 100 years old and replacing it would require wholesale redevelopment and significant changes to planning policy.
Instead, rather than changing architectural design completely, I feel the challenge we need to face is finding a way to adapt our architecture to a warmer climate, without losing the character that makes our towns and villages distinctive.
Our familiar load-bearing materials will continue to play a part in the build process, but there are certainly some elements of architectural design that could easily change in order to combat the main issue of overheating.
One area where I think changes will be seen as summers become warmer, is that our homes may increasingly see more structural work outside the home, to create more permanent shading. Terraces, sheltered courtyards and transitional spaces between inside and outside will be key. As well as being aesthetically pleasing, they also serve the goal of protecting the home from the heat that is trying to permeate within.
Roof design will need greater consideration
Roof design will also become an increasingly important part of the architectural response to warmer summers. Green roofs may become more widespread as they help with insulation, rainwater management and biodiversity, although their suitability will depend on local conditions and maintenance.
Deeper eaves below roofs may also become more popular as they can provide shade, although I don't think pitched roofs need disappear entirely in favour of flat roofs; instead, familiar forms could evolve through changes to their proportions, overhangs and ventilation.
Why ventilation and insulation will become even more important
Anyone self-building or renovating will understand the importance of getting your home's ventilation and insulation right – regardless of climate.
However, with British weather historically erring on the colder, wetter side, most British houses have solid masonry or cavity-insulated walls and relatively small window openings.
This mass of solid masonry walls has traditionally helped keep spaces comfortable by slowing heat transfer, although thermal mass can also absorb and store heat.
Over recent years, sustainability and energy conservation have led to more stringent insulation and airtightness requirements – an approach well demonstrated by the popularity of Passivhaus principles. But, while good home insulation helps retain heat in winter, higher insulation levels alone cannot prevent overheating.
It's no longer just about retaining heat, it's about passive solar gain which is the accumulation of heat through elements such as glazing. As summers get consistently warmer, this will also need to be more carefully controlled.
But, again, it's not suddenly a case of reducing insulation and letting air in. Airtight, well-insulated buildings can still perform well in hot, humid conditions, provided they are adequately ventilated and do not suffer excessive solar gain.
The solution? A tandem approach from the outset whereby glazing, shading and ventilation are all considered together, not as separate entities.
Allowing air to move through buildings will impact design
Natural ventilation, such as cross-ventilation can make a significant difference to overheating and will be a principle we need to consider more often when designing a new home.
Not least of all because these principles have long been used in warmer countries, where buildings have evolved to respond to local climates. However, the challenge in Britain will be how we adopt what works while still retaining heat during the winter.
Including openable glazing on both aspects of the building to allow air to flow through the building from one side to the other, and create a better-lit, more habitable spaces is a good starting point.
Referred to as ‘dual aspect,’ it is already a national planning policy recommendation for housing developments, and is something that should be applied by architects to individual builds too.
Including sufficient space for MVHR will come into play
In self-build houses, Mechanical Ventilation with Heat Recovery (MVHR) installations are increasingly popular and are again, an element that architects will need to consider allowing room for when designing homes.
The systems draw used, stale air through ducts into a heat exchanger and expel it externally, while fresh air is drawn in. Residual heat from the stale air is transferred to the incoming air.
But, as mechanical cooling requires ducting routes, allowances in the space between ceilings and the floors above will need to be made for ducting, which may have an impact on ceiling heights across the home – particularly when designing to a two-storey format.
And, as a heat exchanger needs to be mounted externally, this will also need to be taken into account when considering finishes such as external cladding.
Glazing – one of the biggest design challenges
One of the biggest challenges with homes that are designed to prevent overheating will be in the specification of glazing.
Double and triple glazing perform better than single glazing as the insulating properties of the cavity between planes reduce heat transfer. There are also reflective solar-control glass coatings available that help, but, while technological glazing solutions can assist to a degree, the underlying strategy must be considered in the design at the outset.
Building regulations, in the form of Approved Document O has already introduced requirements addressing overheating in new homes so that appropriate mitigation can be provided from the off. But what does that mean in terms of visual changes to the design of homes?
I do not think there will be a growing predominance of any particular size or type of glazing, but rather a greater consideration of the glazing strategy as a whole: the building’s orientation, surrounding construction and the type of space being lit.
The result need not be a radical departure from traditional British architecture, but rather an evolution in how our homes look and relate to their surroundings.
Orientation of homes on plots may change
Although sunny south-facing gardens with large bi-fold or sliding patio doors have been the design goals of many self-builders and renovators, this combination of larger areas of glazing, warmer summers and restricted openings can cause interior spaces to overheat.
South-facing glazing is the most susceptible to passive solar heating, while east and west-facing glazing can also be impacted by solar gain. This is generally not an issue in winter when the sun is lower in the sky, but can be problematic in summer.
Consequently, far greater attention will need to be paid to the orientation of glazing and its relationship with the sun. Building a new house on a plot gives you the opportunity to choose your orientation, and while south-facing may once have been the number one choice, we may choose instead to choose an alternative option.
That said, during the winter months, it is likely many self-builders would still include a south-facing garden in their design brief, and in these instances, if glazing faces the sun path, then an eaves overhang or some form of shading will help. The glazing can still reap the benefits of passive heat gain from low winter sun while avoiding too much solar gain in the summer.
Blinds, external shutters and deep window reveals may become the norm
I suspect we will also see greater emphasis on specifying blinds and other forms of solar shading as part of the overall window package at the outset, rather than as a decorative addition.
External blinds and canopies are more effective at shielding heat than internal ones because they prevent solar radiation reaching the glass in the first place.
Deep window reveals and external shutters could also help familiar British architectural styles adapt to a warmer climate. These changes would make the boundary between inside and outside less rigid, while providing shade and comfortable outdoor spaces.
And let's not forget the value of a well-designed pergola or a brise soleil which can also provide similar protection, and be integrated with planting to create attractive outdoor shaded areas.
Layouts and room heights may also be impacted
Moving to a home's interior, it's also fair to wonder if there will be change in terms of floorplans and layouts. Broken plan layouts served a purpose in period properties which were heated solely by fireplaces in each room. Internal doors were a must to prevent heat from escaping, but when heat is the very thing you want to remove, will we see a return to open-plan layouts?
It's true that open-plan arrangements allow air to move more freely through a building, as warm air tends to rise and, in tall spaces, can create a ‘stack’ effect, with warm air accumulating at high level in the apex of roofs.
For this to work effectively, however, there ideally needs to be openings within these spaces that allow the warm air to escape, as this can in turn encourage in cooler air to enter through openings at ground floor level.
Vaulted ceilings and high-level vents to assist natural ventilation may therefore become more common, particularly in houses with generous, or double-height spaces.
Landscaping and gardens will need to be considered from the outset
The landscape around our homes will also become increasingly important when designing a home, and something that will need consideration upfront, not just when the build has ended.
Covered terraces, recessed entrances and shaded courtyards could become integral to a home’s original design, with planted screens such as those seen in Japanese cooling methods one option for those looking to deflect heat from reaching inside the home.
Trees, planting and shaded courtyards can make outdoor spaces more comfortable, and drought-tolerant planting, including sedums, may become more attractive.
Water conservation will also need to play a greater role in domestic design. Rainwater harvesting and grey-water reuse could reduce demand on mains supplies, while water features may suit courtyards and garden design, where resources permit.
While design will naturally have to change to adapt to climate change, there isn't one single architectural style or technical solution that will solve overheating.
Each home must respond to its site and brief, balancing orientation, materials, shading, ventilation, daylight, insulation and heating from the outset. British homes will evolve through relatively modest architectural changes, learning from buildings in warmer climates while retaining the character and diversity of our own architectural traditions.
The most successful new and contemporary home designs will make climate responsiveness part of the architecture itself, rather than treating it as a problem to solve after the building is complete.
