Better data and more advanced modelling is presenting the most accurate picture of climate risk yet – and bringing to light new vulnerabilities and priorities for action. Phil Kelly, Brendan McCarthy, Susie Sidley and John Clucas distil the key messages for NHS estates managers

Since 2023, climate change risk assessments have been a formal part of annual governance for NHS trusts in England. This means evaluating how climate change and severe weather could affect their buildings, services and operations, and developing adaptation strategies and action plans to protect people and physical assets. NHS England has produced the Climate Change Risk Assessment tool to help them do this.  

Climate science is evolving, and projections of future weather are becoming more detailed and accurate all the time. So is our understanding of how people and buildings are affected, and what to do about it. That means that each time we update a risk assessment, the picture becomes clearer and more nuanced.  

This year, there have been several leaps forward, including a new set of the weather files that building designers use to calculate energy use and overheating risk, based on more recent data. The Environment Agency also published a new National Flood Risk Assessment, which found that the number of properties at risk of surface water flooding was 43% higher than previously thought. Both of these incorporate the latest climate projections from the Met Office, to provide the most up-to-date assessment of flooding and overheating over the coming decades.   

Combined with new ways of calculating overheating and tighter building regulations, these are changing the game on what we know about climate-related risks and the strategies for managing them.  

Here are the key differences that estates managers need to be aware of, and the implications for their climate risk planning.  

Overheating risk has been underestimated

The new weather files are based on actual data collected between 1994-2023, bringing the baseline forward by a decade, and incorporating the recent run of record-breaking summers. This will likely result in predictions of higher demand for cooling, and a greater risk of summer overheating.  

For spaces without cooling, the definition of comfort has evolved significantly too. Overheating risk used to be calculated as the length of time that internal temperatures would exceed 28°C. But over recent years, there has been wider recognition that comfort is subjective, and closely linked to the average outdoor temperature. Designers now use complex statistical methods for measuring overheating against a shifting “adaptive threshold”, which takes into account not only the duration, but the severity and frequency too. 

When we update climate-related risk assessments, we could discover periods of overheating that will last far longer, or be much more severe than previously expected, especially in combination with the new weather files.  

Our modelling is bringing to light other problems that were previously hidden. For example, we find that internal heat gains are often much higher than original design estimates from 20 or 30 years ago, because there is more electrical equipment in healthcare spaces, and each device generates a small amount of heat. This won’t have been taken into account when ventilation and cooling systems were initially sized. We’re also discovering significant heat build up in transient areas such as corridors or storage rooms, which can transfer through walls and partitions, increasing cooling loads and discomfort in occupied spaces.  

What this means: Estate management strategies will have to bring forward upgrades and replacements of building systems, consider adding cooling in naturally ventilated spaces, and factor increased energy costs into spending forecasts.  

Surface water flooding *may* be a greater threat – but look closely at the data

The Environment Agency’s new flood assessment draws on much better data and improved modelling, and it reveals that the risks to properties to properties in England have been significantly underestimated, particularly from surface water.  

This occurs when heavy downpours overwhelm drainage systems, causing water to overflow into streets and buildings. It is a more widespread threat than river and coastal flooding combined, and a growing one, due to more extreme rainfall events, combined with urban expansion. 

This is a concern for healthcare estates because essential plant is often located below-ground in basements. If water enters and cannot escape, even a small amount could cause damage and disruption to critical systems. Water can also hinder ambulance access or escape routes, making it harder to receive or evacuate patients.   

What this means: Climate-related risk assessments based on the latest data will likely find a greater likelihood of flooding. But this may not tell the whole story – the Environment Agency maps don’t include site-specific features, such as walls, that can significantly influence how surface water behaves. Further analysis may be needed to create a true picture of the risk, and to identify ways of managing it.  

Net Zero targets will add to the adaptation challenge

It’s important to note that adaptations and retrofits that result from updated risk assessments will have to meet new, tougher building standards. These are intended to address not only the risks that climate change presents to healthcare buildings, but their own role in causing it. The NHS Net Zero Building Standard, for example, sets carbon limits for newbuilds, major refurbishments and extensions. Meeting this will involve switching from fossil fuels to fully electric systems, and reducing energy demand as far as possible.  

There is a tension here with increased demand for cooling, and particularly with adding air-conditioning in naturally ventilated spaces. There will also be cost implications. Currently, electricity prices are higher than gas by a factor of four, so switching from gas to electricity for heating and hot water would likely result in higher bills, especially in peak winter months, on top of the capital cost of installing new equipment. In future years, warmer winters could reduce demand for heating, but this would likely be offset by a greater need for cooling, both in capacity and frequency of use.  

What this means: Estates managers need to consider how newer technologies, controls and building management systems will fit into adaptation and decarbonisation plans, spending forecasts and maintenance strategies. 

Taken together, all of this will increase the complexity of climate risk assessments, and potentially the scale of response that is required. But it will also provide the clearest indicator yet of how the healthcare estate is impacted and enable better long-term decision making. At Ridge, we’re continually developing our knowledge too, as our Sustainability Consulting and Flood Modelling teams work with organisations to help them understand their vulnerabilities, prioritise areas for action and devise cost-effective strategies. We know that NHS trusts are already witnessing the effects of hotter summers, on their buildings and on the populations they serve. We’re there to support them to make informed decisions – because forewarned is forearmed. 

If you require support with climate risk assessment or understanding flood risk, please get in touch with our experts. NHS clients can easily procure Ridge, including our Sustainability Consulting services, by direct call-off via the NHS SBS framework (ref: SBS10190). 

Brendan McCarthy leads our climate risk assessment work for healthcare clients, and is national Flood Risk Management lead at Ridge. Contact him at brendanmccarthy@ridge.co.uk

Phil Kelly leads the cross-discipline Net Zero & Circularity practice at Ridge. He is helping clients to decarbonise their assets and portfolios while reducing operational costs. Contact him at philkelly@ridge.co.uk 

Susie Sidley leads the northern Sustainability team covering Manchester and Leeds, and was on the steering group for the UK Green Building Council’s Climate Resilience Roadmap. For any sustainability-related queries, contact her at SSidley@ridge.co.uk  

John Clucas is Healthcare Partner at Ridge, and was previously a senior manager within the NHS leading capital projects. He is available to answer any healthcare project-related queries. Contact him at johnclucas@ridge.co.uk