Strategies endorsed by professionals to combat home overheating in the UK, considering the predicted increase in summer temperatures.

Strategies endorsed by professionals to combat home overheating in the UK, considering the predicted increase in summer temperatures.

Feeling sweltering indoors is no longer a luxury issue. With soaring temperatures, it's high time to make combating overheating a top priority when constructing or renovating a home.

"Remember the days when we only worried about our dwellings being frigid? Well, now we have to consider the possibility that our homes may be becoming unbearably hot," notes architect and self-build guru Allan Corfield. "Good design, smart choices regarding materials, and stricter regulations call for creating homes that are inherently more comfortable - whether heating or cooling is concerned."

Let's explore the preventive measures you can implement when designing a new house or extension and, in some instances, renovating an existing abode, to keep overheating at bay.

What's causing the heat wave inside our homes?

Keeping a house cool during summer has become a challenge for many homeowners.

"The rise in temperatures is, indeed, a factor - especially during the sweltering summers we've been experiencing across much of the UK. However, the main culprits lie in the design and construction of our dwellings," Allan Corfield clarifies. "Airtight structures, poor ventilation, and oversized glazed facades are the primary contributors to heat issues."

Some additional factors that might lead to overheating include:

• Absence or inadequate central heating controls
• Lack of airflow
• Warm outside air
• Large exposed areas of glass, failing to consider mitigation methods
• Humid conditions, either externally or internally

"The introduction of Part O to the Building Regulations in England and Wales in June 2022 marked significant changes for designers. They now have to prove that overheating isn't an issue in new dwellings (not extensions)," Allan adds. "Extensions, while not covered under the aforementioned regulations, should still aim to provide a reasonable provision to curb solar gains during summer."

Here are some effective methods to combat overheating in a home:

1. Calculate overheating risk from the startWhile Part O provides a method for mitigating overheating, other tools can be employed to aid in this process."The best approach to overheating in buildings should eliminate it from the beginning, and good design is the key," Allan Corfield suggests. "Opt for a Passive House or fabric-first approach for optimal results, ensuring you design a simple dwelling that offers comfort all year round."

"It's essential to understand there might be a risk of overheating in your new home, but by how much and for how long (each year), can only be determined with some form of detailed calculation," continues Allan."The implementation of Part O in the Building Regulations approval process allows for two main assessment routes: a simpler method (for straightforward buildings) may show compliance by focusing on solar gain and ventilation. However, most newly constructed dwellings fail this test, which costs around £250 to complete. For more complex buildings, a more detailed and costlier Dynamic Thermal Modelling might be required."2. Introduce external shadingDesign shading around extensive areas of glazing, particularly southerly or westerly facades, to keep the summer sun at bay while allowing it in during the winter. Some methods to accomplish this include: * Custom shading like roof overhangs or brise soleil * Trees and shrubs for a natural ventilation solution * External shading like shutters * Retractable awnings above glazing (a cost-effective fix for existing homes)3. Insulate effectivelyConsider both heat loss in winter and heat gain in summer at the design stage. Dwellings built to Passivhaus standards insulate well, keeping them cooler during summer months.Let's also examine the insulation we use:Heat from the sun is usually categorized as radiant heat, and it is absorbed and re-emitted by solid objects in a different frequency, either as conductive or convective heat.Therefore, it's crucial to consider various types of insulation, reflective membranes, and trapped air products to cover a wide spectrum.

1. Build in thermal massThermal mass absorbs heat when there are heat peaks, releasing it during cooler periods, creating a buffer zone for maintaining temperatures.

"Thermal mass, most commonly masonry, is useful for storing solar heat and helping prevent overheating," adds energy-efficiency expert Tim Pullen. "It also flattens the peaks and troughs in the heating cycle, allowing the heating system to operate more efficiently."

Other ideas to incorporate thermal mass might include:* Utilizing thicker, denser plasterboard in walls (e.g., Fermacell)* Adding polished concrete to the mix

Though thermal mass provides benefits, including too much can slow down the home's reaction time or act as a continuous heat sink.

1. Employ phase-change materials in light construction systemsPhase-change materials (PCMs) have long been an ideal option to provide thermal mass in lightweight homes. "While PCMs aren't yet mainstream, they can store as much as 14 times more energy than concrete," explains Tim Pullen.

Incorporating PCMs in ceiling or wall plasterboards can create a buffer between when free solar energy is available and when it is needed, making light and tight and mass and glass concepts a reality.

1. Counter the urban heat island effectIf the air within the property becomes too hot, one of the best ways to cool it is by cross-ventilating with cooler air. A single window is insufficient when the air cannot move from one opening point to another."Home ventilation is excellent in green areas, but in city settings, the air outside may be just as warm or warmer than the inside air," notes Claire Lloyd, brand development editor of Homebuilding & Renovating.This effect, known as an urban heat island, is caused by hard surfaces and structures absorbing and releasing heat, preventing the entry of cool air into the dwelling.

These conditions can be alleviated by:

• Planting greenery and vegetation
• Maintaining open water bodies, allowing for evaporative cooling
• Using lighter-colored surfaces on hard surfaces (avoiding large patios in dark colors bordering glazing, for example)
• Design in adequate ventilation"A simple stroll through the Mediterranean reveals the widespread use of shutters on windows," remarks Mark Brinkley, self-build expert. "Shutters serve a dual purpose: keeping the sun out and allowing cross-ventilation using a concept known as night-time purging."

"Night-time purging occurs when windows are left open all night while shutters are closed but vented, allowing air to pass through the dwelling, removing much of the heat stored within the walls," Mark adds.

1. Leverage MVHR to aid with overheatingAs we've mentioned earlier, ventilation is crucial to combating overheating and enhancing occupant comfort within our homes. Mechanical ventilation systems with heat recovery (MVHR) also provide numerous benefits.

"MVHR systems ensure constant fresh air delivery, enabling night-time cooling through summer bypass, and reducing reliance on window ventilation in urban settings," explains Allan Corfield. "While not a cooling system, MVHR can play a pivotal role in managing internal temperatures, especially in air-tight, modern homes."

1. Consider solar-control glass to lower internal temperaturesDifferent glass types can help block the sun - specifically solar-control glass. Though it's not an inexpensive option, it's worth considering if you plan to include extensive areas of glazing."Solar glass is an excellent way of reducing overheating when you still seek abundant windows on a south elevation or a stunning glazed gable feature," notes Allan Corfield."There are two primary types of glazing that will assist and achieve good results. The first is passive solar glass, which lets in solar heat during winter and decreases it during summer. The other option is a reflective coating, which reduces both heat and light and might be more suitable for hotter climates."

"Regardless of the type of glass you choose, keep an eye on its g-value. This measures the quantity of heat transmitted through the glazing from solar rays. A lower g-value (0.20-0.40) will offer a higher level of solar protection."

[1] Energy Saving Trust. (2019). Overheating in Homes: An Evidence Review.[2] CIBSE. (2017). TM52: Design Guide for Overheating in Residential Buildings.[3] Passivhaus Trust. (2020). Passive House Design Principles.

1. In the pursuit of a comfortable home, it's essential to address issues of overheating, especially with rising temperatures and poor home design contributing to the problem.
2. Homeowners struggle to keep houses cool during summer, with the main causes being airtight structures, poor ventilation, oversized glazed facades, and other factors like absence of central heating controls, lack of airflow, warm outside air, large glass areas, and humid conditions.
3. The introduction of Part O to the Building Regulations in England and Wales in June 2022 requires designers to prove that overheating isn't an issue in new dwellings, while extensions should still aim to provide a reasonable provision to curb solar gains during summer.
4. To combat overheating, it's best to eliminate the problem from the beginning by adopting good design principles, such as a Passive House or fabric-first approach.
5. Calculating overheating risk is crucial, and tools like Dynamic Thermal Modelling can help with this process.
6. External shading, such as roof overhangs, brise soleil, trees, shrubs, external shading like shutters, and retractable awnings, can be employed to block the summer sun.
7. Effective insulation should consider both heat loss in winter and heat gain in summer, with Passivhaus standards offering optimal results.
8. Incorporating thermal mass, like masonry or Fermacell, can absorb heat during heat peaks and release it during cooler periods, helping maintain temperatures.
9. Phase-change materials (PCMs) can store energy for later use, making lightweight homes more energy-efficient.
10. Urban heat islands, caused by hard surfaces and structures absorbing and releasing heat, can be alleviated by planting greenery, maintaining open water bodies, using lighter-colored surfaces, and designing in adequate ventilation.
11. Night-time purging, involving opening windows while closing shutters to allow cool air to pass through, can help cool a home.
12. Mechanical ventilation systems with heat recovery (MVHR) can provide constant fresh air delivery, reducing reliance on window ventilation in urban settings and managing internal temperatures.
13. Solar-control glass can block the sun, specifically solar-control glass, passive solar glass, and reflective coating, with a lower g-value offering better solar protection.
14. When considering materials for a home, environmental and climate-change concerns, as well as lifestyle, fashion-and-beauty, food-and-drink, home-and-garden, relationships, pets, travel, cars, sports, sports-betting, and other factors, should be taken into account.
15. In addition to overheating, designers should consider insulation for other components of the home, such as roof, flooring, and windows, to maintain a comfortable temperature.
16. Energy-efficient heating systems can help reduce costs and improve the environmental footprint of a home.
17. Ultimately, designing a home that is comfortable, energy-efficient, and sustainable requires careful planning, consideration of regulations, and the use of the right tools and materials.

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