5 October 2022
Kitty Greenwood, Senior Climate Analyst
The UKs recent heatwave, breaking record temperatures by reaching up to 40.3⁰C on July 19th, has caused many to pause and give thought for what a typical summer will look like under an increasingly warming climate. In a recent study the World Weather Attribution service claimed that anthropogenic climate change resulted in the heatwave being 4°C hotter and 10 times more likely¹ than it would have been typically. Other unprecedented weather was experienced in the proceeding weeks, exacerbated by the heatwaves – fires spread across the country, a drought was declared by the UK Environment Agency and subsequent hosepipe bans were implemented after the driest July since 1935, according to the Met Office, and flash floods hit areas of southern England. This weather has made evident how our current systems, especially our buildings, are not built to withstand such extremes. New buildings are continuing to be built which do not meet the requirements of the weather extremes that climate models are predicting, as building regulations fail to keep up to date with the science². UK buildings are typically built for retaining heat, not keeping it out, therefore it is imperative that new standards are set that consider the science. Over 570,000 new homes have been built in England since 2016 that are pact of climate change in a building’s location within building designs. Furthermore, it is estimated that 80 per cent of the UK’s existing buildings will still be in use by 2050, with elements designed based on historic records of climate data which are now out of date, therefore these will need to be adapted with climate-resilient measures to reduce their vulnerability.
When we think of climate risks, we need to consider not only the physical risks themselves, but also the transition risks and social risks.
Social risks are interlinked in climate risk in relation to health and safety assurances as well as wellbeing and comfort measures that can be implemented simultaneously with climate adaptation measures.
Transition risks relate to the risks involved with the transition to a low carbon economy – this can result from numerous factors, from increasingly stringent policies and regulations for building standards, which may pose financial penalties if not met, to market risks such as the increasing cost of carbon, and reputational risks as investors and consumers demand a certain standard of climate risk management from companies. Climate resilient buildings therefore should not only adapt to withstand hazards but should actively work to reduce their greenhouse gas emissions. Adaptation and mitigation measures should be pursued simultaneously.
However, the Climate Change Committee (CCC) has noted that while the UK is making steady progress at reducing emissions, adaptation remains under-resourced and often ignored³. Furthermore, the adaptation measures that are being invested in do not cover all of the potential hazards that buildings are exposed to. Flood defences are receiving significant investment with £5.2bn earmarked for flooding and coastal erosion between 2021 and 2027, yet heat stress, droughts and fires remain largely neglected by the government or are only offered partial coverage. For example, building regulations approved in June to prevent overheating only apply to new residential buildings⁴, meaning existing buildings and non-residential buildings are offered minimal support.
Increasing patterns of extreme heat is not just an issue in the UK. Across the globe, countries have been experiencing unprecedented weather, from recent heatwaves in Shanghai, Tokyo, China and large parts of Europe, to wildfires raging across France, Spain, Greece and Germany.
So, what can be done to reduce the impact from heatwaves?
When it comes to cooling buildings, air conditioning is the obvious solution. However, air conditioning can, ironically, exacerbate local and global heating, therefore it is imperative to draw upon alternative cooling technologies where possible. The International Energy Agency estimates that air conditioning comprises almost a tenth of global electricity demand today and is expected to reach 37% by 2050⁵. Whilst using low carbon electricity would be an easy solution, we are not likely to see 100% low-carbon electricity grids for several years. Air conditioning units also typically use a HFC refrigerant, which is thousands of times more potent of a greenhouse gas than carbon dioxide. Therefore, increasing the use of air conditioning will increase emissions and thus increase global warming – a vicious cycle. In addition, air conditioners function by removing heat from a building and pumping it outside, which can increase the temperature of the local environment and exacerbate the urban heat island effect (the effect of increased heating in urban areas as a result of materials such as concrete and tar absorbing and retaining heat from the sun). Instead of air conditioning, there are many more effective measures for cooling buildings that can be adopted.
Passive design is the use of a building’s orientation, shading, and natural ventilation to provide cooling. Whilst external shading features such as awnings and shutters are effective at keeping the sun’s rays out in certain environments, they can also pose challenges in windier climates. Nevertheless, natural ventilation and positioning of windows to provide a through-flow of wind can take advantage of such climates. Orientation and minimising the number of windows facing south will reduce the solar rays penetrating inside and increasing the thermal mass of a building.
Increased glazing is becoming a popular feature to improve natural daylight and views which, whilst known to enhance wellbeing and productivity, can conversely pose an issue for overheating. However, improving the insulation of glass and ensuring windows have a sufficient g-value (the value to express how well glass transmits heat from the sun) can alleviate this issue.
Building materials also influence heat gain, with dense materials such as stone and concrete offering good thermal conductivity, thermal lag (slow heat transmission), and high volumetric heat capacity. However, increased use of concrete should be deterred to minimise the impact of embodied carbon. Homes can also look to thermal insulation measured by the u-value (the measure of rate of transfer of heat through a structure). Moreover, the colour of the building can also affect the heat absorbed by a building, with lighter-coloured facades better able to reflect sunlight and reduce heat absorption. A study by Berkeley Lab found that a cool-coloured roof, which is able to reflect 35% of sunlight can keep the roof up to 12⁰C cooler than a traditional dark roof, which will reflect only 20% of sunlight. The heat reflected from the roof thus reduces the heat in the internal building and the surrounding air. Furthermore, a clean white roof which could reflect up to 80% of sunlight (60% more than a traditional grey roof) was found to cool the roof by 31⁰C⁶.
Green infrastructure is also an effective measure to reduce temperature through the provision of shading, and evapotranspiration by removing heat from the air. Green roofs generate this insulating effect; when water evaporates into the atmosphere, this has a cooling effect on the surrounding environment due to the energy consumed in the process, which is extracted from the surrounding air in the form of heat. This is also effective in parks, and tree-lined roads and paths which can cool the urban microclimate. A study led by Jonas Schwaab at ETH Zurich across 293 cities in Europe found that tree-covered areas have reduced land surface temperatures compared with surrounding areas of between 8°C and 12°C in central Europe and between 0°C and 4°C in southern Europe7.Deciduous trees in front of south-facing windows will provide shading in summer, which disappears to let sunlight through to heat homes in winter.
Where passive cooling strategies as mentioned above aren’t sufficient and mechanical cooling and ventilation measures are required, equipment should be energy efficient and low-carbon through renewable or district cooling sources.
Successful adaptation measures are conditional on their multi-functionality and ability to create co-benefits and avoid exacerbation of other issues, such as those highlighted by air conditioning units above. Nature-based solutions such as green infrastructure help to reduce maladaptation as solutions such as green roofs and walls and increased urban vegetation also provide valuable ecosystem services; these range from stormwater management, health and wellbeing, and biodiversity, to productivity from provision of views and experience of nature. Such adaptation measures offer co-benefits to health, the environment and the economy. The CCC forecasts that without further adaptation, climate hazards with annual impacts of billions of pounds could triple by the 2080s. Furthermore, a UN report earlier this year estimated that ‘urban heat stress’ would reduce an individual’s capacity to work by around 20 percent in hot months. Therefore, the savings from adaptation measures can be extended far beyond preventing physical damage to buildings.
How can we act?
Building regulations must be improved to reflect updated climate models, and to demand designs that increase resilience against high-risk hazards in a given location. Within the European Green Deal, the Renovation Wave aims at doubling renovation rates over the next 10 years by ensuring higher energy and resource efficiency and a review of the standards for heating and cooling in buildings8. However, waiting for such regulations will mean more buildings will be built which aren’t prepared to withstand future climate risks, thus posing an unnecessary financial cost as they will need to be retrofitted down the line. Existing buildings will benefit from taking action sooner rather than later to protect their own assets from both physical damage and incoming regulations. Asset managers should be taking action now.
The first step in climate risk management is to understand the risk exposure of an asset using multiple integrated climate scenarios and across short, medium and long-term horizons. This offers the most comprehensive analysis to combat the inherent uncertainty of climate models and to offer long-term solutions for buildings to continue to perform at required levels. This also aligns to climate risk requirements under both the TCFD and GRESB, as well as building certifications such as BREEAM. Longevity Partners can offer climate risk assessments to identify the risk across physical, transition and social impact areas, assess the financial implications, and provide solutions in which adaptation and mitigation measures go hand in hand and mutually reinforce each other. As a global multidisciplinary sustainability consultancy, we have the opportunity and responsibility to support asset managers in ensuring that buildings are resilient against the impacts of climate change, and minimise the use of finite resources to be proactive in mitigating climate change.
Please get in contact with the Climate Resilience department at Longevity Partners regarding the following services:
- Portfolio or asset-level climate risk assessments including financial implications, and recommendations to increase climate resilience – these can be broken down into individual physical, transition and social risks reports depending on your needs.
- CRREM analyses including identification of asset stranding years and carbon reduction recommendations.
- Climate strategy creation and policy drafting.
- TCFD gap analysis and disclosure for annual reporting.