Protecting Properties from Heat

Heat is a growing issue from propert...

Heat can make us less productive, impact our sleep and lead to numerous health issues. Given that the UK has a warming climate and a housing stock that is ill-suited to dealing with temperatures above 25℃, we all need to be more active in managing the risk of overheating in our homes. Thankfully, the following approaches can be used - at least for the next few years - to keep temperatures in most residential properties bearable:

Passive cooling techniques

By far the easiest and most cost-effective way to reduce the risk of overheating in your home is to employ passive cooling techniques. Recent research suggests that such methods – which include creating natural ventilation and shading – can alone be effective at preventing properties form becoming dangerously hot during heatwaves (and / or significantly reduce electricity costs in homes with air conditioning). For the best results, try to open windows during the night and early morning (when outside temperatures are coolest) and draw blinds or shades at the hottest part of the day or, for windows facing East, West or South, when the sun is shining directly on them. While research indicates that external shutters or awnings are most effective at blocking heat, indoor pull-down shades or blinds also make a difference, particularly when combined with side tracks. Note, however, that dark curtains and metal blinds can absorb heat and increase room temperature. If they cannot be replaced, consider placing a reflective material between the curtain / blind and the window. Another approach involves lightening the colour of your roof so that it reflects more of the Sun’s energy. While the sight of a light or even white roof is fairly unusual in the UK, it is relatively common in many hotter parts of the world and could lower the temperature within your home by several degrees.

Plant trees

Trees provide welcome shade and cool their surroundings via transpiration (the release, through foliage, of water vapour that lowers temperatures when it evaporates). Deciduous trees are a good choice for many homes as they can provide shade in summer and allow light to enter during winter. Trees also provide numerous additional benefits, such as promoting biodiversity, cleaning the air and reducing flood risk.

Remove sources of heat

During a heatwave, turn off non-essential lights and electrical equipment, and avoid cooking anything that requires extended use of your oven or stove. Replacing all your lights with LEDs will not only save you money by reducing your energy bill but will produce far less waste heat.

Retrofit

Few homes in the UK have fixed cooling systems such as air conditioning. These are typically expensive to install and run and may not be suitable for older homes. Current supply chain issues also mean that they may be difficult to source. Moreover, the energy consumed by air conditioning units exacerbates global warming and places an extra strain on electricity grids during hot days. They also generate large amounts of waste heat that will increase temperatures around your home. Smart windows and better insulation can help to keep heat out, while an air source heat pump can be used to cool your home.

Location

In general, the further south in Britain and more urban the location, the higher the temperatures a property is likely to be exposed to. Perhaps surprisingly, the temperatures experienced by neighbourhoods within the same city can vary by several degrees depending on their attributes. In general, locations with low levels of natural covering tend to experience higher temperatures. There is, however, some evidence that properties located near a river or lake benefit from a cooling microclimate. Infrastructure that is critical to the delivery of services such as mobile phone coverage and water can be disrupted by heat. Similarly, critical components of the energy network, including solar panels and transmission lines, become less efficient at higher temperatures, making power cuts more likely.

The Urban Heat Island Effect

In general, urban locations tend experience higher temperatures than their rural surroundings, particularly at night. Known as the 'urban heat island' effect, this results from the release of waste heat from vehicles and buildings, as well as the way that artificial surfaces such as roads and walls absorb and then release solar radiation.

Design

Generally speaking, smaller and more modern properties (especially flats) are more prone to overheating, reflecting the prevalence of features such as low ceiling heights (which hinder air circulation), higher density of dwellings, planning policies that promote access to daylight and high levels of glazing. Research also indicates that loft conversions are highly vulnerable to overheating. Interestingly, measures designed to improve the energy performance of buildings during winter can inadvertently lead to overheating during the summer. For instance, better insulated properties are typically harder to cool down. Just as it is more efficient to heat the areas you live in rather than the whole house during winter, it may make sense to check that there is at least one room (especially a bedroom) that can be kept cool and can offer a refuge during hot weather.

Orientation

The direction that key living areas face will impact the amount of natural light that enters your home. Windows facing east or west are harder to shade as the sun is lower in the sky as it rises and sets. Single aspect flats (in which all windows are on the same facade) can be difficult to ventilate and could be exposed to large amounts of sunlight if they face east, south or west.

Windows

Ensure that windows allow large openings and can be easily operated, and that there are no reasons to avoid doing so, particularly at night. Noise, pollution and safety concerns may all hinder your ability to do this. This is often a problem in tall buildings, where window openings are typically restricted for safety reasons. You may also want to look for properties that have – or could easily be retrofitted with – effective shading.

Protecting your home from fire

Many people overlook the threat of wildfire in the UK, but fire services deal with tens of thousands of them each year, while 'severe wildfire' has been included in the National Risk Register since 2013. You can take several steps to reduce your property's vulnerability to wildfire, including: Create a buffer zone (of at least 10 metres if possible) around your house. This should be well-irrigated, free of flammable material and (ideally) covered in non-combustible materials such as gravel or concrete. (Alternatively, keep any lawns adjacent to your property trimmed to 75mm or less.) This makes it less likely that a fire will spread to your home (either from embers or flames) and creates a safe area from which firefighters can tackle a blaze on surrounding land. Maintain water sources like hydrants, ponds and pools and make sure that they are accessible. Ensure that emergency services can access your property and that your address signs are clearly visible from access roads. Make a plan for what you will do in case of an emergency evacuation, scope-out escape routes and create a 'go bag' with essential supplies that you can easily take with you. Remove flammable items (e.g., cushions from outside spaces), clear gutters and use wire mesh to cover vents and other openings in your property's structure (this prevents embers from entering the building). Store any flammable material in appropriate containers within a fire-resistant shed or garage. Be extremely careful when lighting fires or barbecues, particularly when high temperatures, high winds and low humidity are present or forecast. Always have a source of water nearby, never leave a fire unattended and make sure that ashes are completely extinguished before disposing of them. Remain vigilant of power lines around your property. If you spot a tree or branch that could strike one (and cause a fire) let your utility know immediately.

You can assess the overheating risk of any UK property through the PropEco Data Explorer and PropEco API.

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