Transport for London                            HRSC0053

Written evidence submitted by Transport for London

Environmental Audit Committee - inquiry on heat resilience and sustainable cooling

1             About TfL

1.1        TfL is the integrated transport authority responsible for meeting Mayor of London’s strategy and commitments on transport in London. We run the day-to-day operation of the Capital’s public transport network and manage London’s main roads. We are guided by the Mayor's Transport Strategy and its target that 80% of all journeys will be made on foot, by cycle or using public transport by 2041.

1.2        Our services and offering includes:

• Bus fleet of around 9,300 vehicles operating across 675 routes
• London Underground has 11 lines covering 402km and serving 272 stations
• Docklands Light Railway
• London Overground
• Elizabeth line
• London Trams
• TfL Roads
• River (we manage 8 piers along the Thames)
• London Dial-a-Ride
• Coaches and Victoria Coach Station
• Cycling and Walking
• London Cable Car
• Taxis and private hire
• London Transport Museum
• Commercial property development.  London’s third biggest landowner and second biggest landlord, delivering 20,000 new homes (50% affordable) for London.

2             What evidence exists on the relationship between heat and human health (mortality and morbidity), and which communities are worst affected?

2.1        TfL recently undertook a review of six studies (from 2005 to 2022 and across four continents), examining the relationship between temperature and health.

2.2        Most, if not all, the studies reviewed found that:

• there will be an increase in heat-related mortality / morbidity and a decrease in cold-related mortality / morbidity by the end of the 21st century due to climate change 
• the impact of low temperatures on mortality / morbidity rates is more significant than the impact of high temperatures
• certain subsections of the population are more vulnerable to temperature-related illness/death/accidents – including the elderly, the very young, those with limited mobility, those who work outdoors and those of a lower socio-economic background
• high temperatures are generally associated with respiratory mortality / morbidity, whereas low temperatures are associated with cardiovascular mortality / morbidity
• high temperatures are associated with increased risk of injuries and accidents

2.3        Additionally, several studies identified key threshold temperatures that were found to increase death, physical and mental illness, and accidents by certain amounts. For example, temperatures above 20ºC and below 2ºC in London were found to increase the risk of temperature-related death, illness and accidents.

2.4        Other studies showed that even a 1ºC increase or decrease in typical seasonal temperatures could have an impact. For example, a 1ºC increase led to an 18% increase in morbidity risk and 35% increase in mortality risk in Australia. Following this review, we are exploring whether our data can support research into the impacts of high temperatures on customer illness, as well as exploring whether high temperatures affect staff health.

2.5        A study commissioned by the Climate Change Committee identified that, under current weather conditions, most representative buildings failed the bedroom overheating criterion, representing around 55% of the UK housing stock (15.7 million homes).[1] Under a 2°C global warming scenario, all homes outside Scotland failed the bedroom criterion.

2.6        The London Legacy Development Corporation’s Post Occupancy Evaluation study monitored recently completed newbuild homes (built prior to current part O of the building regulations).[2] The study found evidence of overheating in nine of the 11 monitored properties, with evidence of severe overheating in three of the 11 properties.

2.7        Our third Adaptation Reporting Power submission to Defra identified five risks to people scored as major or above today: the majority (four out of five) are linked to extreme high temperatures. This increases to 11 risks in the 2050s and 13 in the 2080s.[3]

3             How can sustainable cooling solutions and adaptation strategies be implemented in such a way as to minimise overheating, reduce energy consumption and prevent overloading of the electricity grid during peak demand?

3.1        The London Plan and the 2022 Energy Assessment Guidance set out a cooling hierarchy that prioritises passive solutions and discourages active cooling:

• Reduce the amount of heat entering the building through orientation, shading, high albedo materials, fenestration, insulation and the provision of green infrastructure.
• Minimise internal heat generation through energy efficient design
• Manage the heat within the building through exposed internal thermal mass and high ceilings
• Provide passive ventilation
• Provide mechanical ventilation (MVHR) - Mechanical ventilation can be used to make use of ‘free cooling’ where the outside air temperature is below that in the building during summer months. This will require a by-pass on the heat recovery system for summer mode operation.
• Provide active cooling systems - The increased use of air conditioning systems is generally not supported, as these have significant energy requirements and, under conventional operation, expel hot air, thereby adding to the urban heat island effect. However, once passive measures have been prioritised if there is still a need for active systems, these should be designed in a very efficient way and should aim to reuse the waste heat they produce.

3.2        In line with the London Plan’s cooling hierarchy, TfL prioritises passive cooling techniques where possible. These could include targeted green infrastructure, such as trees to provide shade or green roofs to reduce solar gain. Green infrastructure solutions also have additional benefits, such as supporting biodiversity and helping to reduce surface water flood risk. These benefits are recognised, for example, in our Healthy Streets guidance.[4]

3.3        Passive cooling and ventilation systems were also considered as part of the design for the Elizabeth line, which ensured that:

• air temperatures for central section tunnels do not exceed 40ºC, unless in extreme conditions
• platform cooling could be installed later, should there be a need to maintain temperatures at 27ºC or below
• the internal air temperature of trains does not exceed 29ºC, unless under extreme conditions
• station buildings and infrastructure (non-platform spaces) minimise the need for cooling as far as possible

3.4        Minimising heat generation is also crucial. For example, TfL has rolled out regenerative braking across most of its London Underground lines, reducing the amount of heat generated by trains.

3.5        Where active cooling techniques are required, these should be informed by climate projections data, to help ensure that they do not over-perform and minimise carbon emissions. The Met Office’s climate projection (UKCP18) data is world-leading but is complex to access and use appropriately. To make the most of this data, the Met Office should work with relevant public sector and industry bodies to develop a threshold exceedance frequency generator, like that provided for UKCP09.

3.6        The Climate Change Committee commissioned a study on overheating risk in existing UK homes, which covers in detail the effectiveness and cost of a range of measures, including passive measures.[5]

3.7        We also intend to explore the potential for waste heat projects, which take heat from the London Underground to provide cheaper, greener heat to local communities, to help reduce temperatures during the summer by reversing the direction of the fan in the ventilation shaft.

3.8        Crucial to the successful implementation of all these initiatives and measures is the development and implementation of a holistic strategy that helps avoid perverse outcomes (such as climate change adaptation at the expense of climate change mitigation). TfL’s Corporate Environment Plan helps TfL to consider the environment as a whole and sets targets and actions for the business to achieve and implement.[6] A key part of this is embedding environmental considerations into decision-making across the business, for example, through a recent refresh of TfL’s Safety, Health and Environment Management System and a forthcoming update to our project management process. Further information on TfL’s work on adaptation can be found in our recent Adaptation Plan.[7]

4             What actions can be taken to protect those most vulnerable to the impacts of extreme heat?

4.1        During periods of extreme heat TfL’s infrastructure (transport network and property holdings), staff and customers are affected. With over 5 million journeys across TfL’s services each day, many people vulnerable to the impacts of high temperatures use our network.

4.2        Through our strategies, policies and plans, we aim to protect our staff, customers and assets from extreme heat. For example:

• Design of new infrastructure: such as our Northern Line Extension, which was designed with large draught relief shafts to provide natural ventilation and cooling as trains move through the tunnels. Station fans supplement the passive cooling systems, by extracting warm air from under-platform ventilation ducts, once the tunnels exceed a certain temperature
• Air conditioning and cooling: we have installed air conditioning on London Overground trains, our S-Stock train fleet, and our bus driver cabs. The new Piccadilly Line fleet will also have air conditioning. Currently, the top floor of our double deck bus passenger saloons are fitted with lower-energy demand air cooling systems: this will be expanded to our entire bus fleet from 2024.
• Research and innovation: such as our trial of new cooling panel technology at Holborn station.[8] TfL also conducted an extensive study in partnership with University College London, to understand thermal comfort. The results informed several measures that have now been added to TfL’s Bus Vehicle Specification for new buses. This includes automatic interior temperature control based on ambient/outside temperatures, monitoring CO2 levels onboard, painting bus roofs white to be more heat-reflective, and open/close vents for fresh air circulation.
• Network Management and Resilience: such as our 321 Weather Plan framework to manage staff and assets. Bespoke, twice-daily 5-day look-ahead weather forecasts are reviewed, and if risk thresholds are reached, the Hot Weather 321 Process will be put in place. This counts down from Day 3 to Day 1, when the hot weather is forecast to arrive. The Control Centre Duty Manager (CCDM) and Senior Operating Officer (SOO) make the decision to implement the 321 process and will ensure this decision is communicated to all parties.
• Communications: we use our communication channels to inform customers of extreme heat and, where appropriate, advise customers to check before they travel, to carry water with them and not to board TfL services if they feel unwell. In future, we would like to build the capability to have real-time temperatures displayed in stations to allow customers to make informed decisions of whether travel is appropriate for them.
• Green infrastructure: we are working to increase tree coverage on our network by 1% each year between 2016 and 2025. We currently have approximately 25,000 street trees, which provide shade and localised cooling for pedestrians and cyclists.

4.3        TfL’s leadership in this area is not matched by Government leadership. TfL has identified several areas where national government could support its work on heat resilience.

Collaborative action

• Coordinate the creation of strategic groups for heat, learning from the experience of the London Surface Water Flooding Strategic Group
• Create templates for sharing best practice resilience measures across organisations and industry
• Continue to raise awareness of heat impacts and what can be done through Government channels
• Create a pan- London and national approach to help sectors understand their interdependencies, and guidance on how sectors should work together to tackle their heat risk and opportunities

Funding

• Increase the amount of grant funding available for resilience and adaptation measures
• Provide templates and proformas to allow for easier pooling of public sector money for adaptation measures
• Remove barriers such as VAT on the financial contributions that the private sector makes towards public sector adaptation measures

Data, skills and knowledge

• Provide grant funding to institutes, universities and organisations to develop programmes for climate change adaptation and resilience skills and training
• Make the Adaptation Reporting Power mandatory, rather than voluntary, and expanded to include as broad a range of UK infrastructure owners and operators as possible, so that the UK has a complete view of risks and opportunities and is able to develop a comprehensive plan for adaptation
• Create templates, methodologies and guidance on what data should be collected for adaptation and resilience
• Finally, it would be beneficial for the Met Office UKCP18 data to be more accessible and usable, to help us better design our infrastructure for future climate scenarios.

5             To what extent do the Government’s Climate Change Risk Assessment and National Adaptation Programme (as well as other related strategies such as the Net Zero Strategy and Heat and Buildings Strategy) identify and address the risks from extreme heat? (Note: The third NAP, covering the five-year period from 2023-2028, is expected to be published in the summer of 2023)

5.1        The Climate Change Committee is clear that the UK’s net zero commitments cannot be met without adaptation to climate change. This is reflected in the Government’s third Climate Change Risk Assessment (CCRA3) and in several of the chapters of the third National Adaptation Programme (NAP3). However, neither NAP3 nor the Heat and Buildings Strategy addresses the potential perverse outcome of increased carbon emissions from active cooling of the UK’s transport networks.

5.2        Both CCRA3 and NAP3 highlight heat risks. However, despite transport-sector-wide input into NAP3 development, very few transport sector stakeholders are allocated actions. Given how interconnected and interdependent that the UK’s transport networks are, this is a major oversight. Part of this may reflect the fact that the Adaptation Reporting Power was out of phase with CCRA3 development. This is now being addressed for the fourth reporting round, but given the critical importance of the CCRA process, the Adaptation Reporting Power must be made mandatory as soon as possible.

5.3        In addition, the NAP3 vision for the UK is vague, with no indication of what “fully adapted” and “resilience” look like in practice, or any commitments to funding this vision. For example, it is unclear from NAP3 to what extent transport networks are expected to run services during extreme heat events (particularly urban transport networks that suffer from the added impacts of the Urban Heat Island effect), or how the adaptation measures to achieve this would be funded.

5.4        TfL welcomes the NAP3 action of the development of a transport sector adaptation strategy. This has been long needed, but must extend to all transport sector organisations, not just the limited sub-set of organisations allocated actions in NAP3.

5.5        NAP3 does not appear to set out a strategy to address existing homes (including those built recently) nor does it provide a strategy for cooling shelters. There appears therefore to be a significant gap in how it serves the most vulnerable in society.

5.6        Considerable improvements in the skills and knowledge available in the workforce are required to be able to adapt to climate impacts, such as extreme heat. This is a major issue that requires coordinated effort and investment from Government and industry but is only very briefly touched on in NAP3.

6             Does the current planning framework do enough to encourage heat resilience measures such as cooling shelters, water bodies, green infrastructure and shading to be integrated into urban planning? Where such measures are incorporated, how accessible and successful are they?

6.1        The London Plan goes further towards addressing heat risk than the National Planning Policy Framework, for example, in the cooling hierarchy and prioritisation of green infrastructure. Regarding transport, the London Plan requires Local Planning Authorities to “promote and demonstrate the application of the Mayor’s Healthy Streets Approach to improve health and reduce health inequalities”, and development proposals should “demonstrate how they will deliver improvements that support the ten Healthy Streets Indicators in line with Transport for London guidance”. 

6.2        There is currently little post-occupancy evaluation of newbuild homes. This should change, to determine whether current regulations (for example part O of the building regulations) are effective in new buildings. Newbuild homes built shortly before part O of the building regulations appear to have a significant performance gap on summer overheating.

6.3        For newbuild homes in London Urban Greening Factor (UGF) and Biodiversity Net Gain (BNG) will likely positively affect newbuild, however, a key challenge is the maintenance of new trees and planting.

7             What can be done to protect the UK’s existing public and private sector housing stock from the impacts of extreme heat while ensuring that homes are sufficiently warm in the winter months?

7.1        The use of naturally dense materials (compressed wood-fibre boards) or other heavy-weight materials help to increase the buildings decrement factor and slow down the transmission of direct sunlight through from the outside to the inside. Promotion of these types of materials instead of lightweight insulation will help with maintaining year-round comfortable internal conditions.

8             What role might reversible heat pumps (which can act as both heating and cooling systems) and other emerging technological solutions, such as the development of smart materials, play in meeting future cooling demands?

8.1        These will only be effective for cooling where building conditions are adjusted by an “all air” system. Cooling through radiators or underfloor heating (UFH) is generally not suitable due to condensation forming when the dew point drops too low. This will lead to visible and non-visible building fabric damage (above the floor for radiators and below the floor for UFH). 

8.2        It should also be noted that passive measures must come first.  Using heat pumps for cooling will increase energy demand (leading to increased bills / higher fuel poverty, as well as contributing further to climate change), and will result in localised heat build-up (as the heat pump cools a building, it rejects the accumulated heat to the atmosphere), exacerbating London’s urban heat island effect.

9             How can cleaner refrigerants with low or zero global warming potentials support the UK’s cooling needs while contributing to the national emission reduction targets?

9.1        See above, but also note that when being used, heat pumps must use low/zero Global Warming Potential refrigerants or there is a risk of increasing climate change, due to poor maintenance resulting in increased refrigerant leaks.

10         Does the Government’s Future Homes Standard adequately consider overheating in homes? If not, what additional elements should it include?

10.1    During the 2020 consultation on the Future Homes Standard there were no questions on controlling overheating: this was deferred to the new Part O, representing a missed opportunity. In addition, Part O does not consider the broader public realm and its contribution to reducing overheating of buildings.

10.2    The type of material used to compose the building must be carefully considered to ensure slow transmission of external conditions to the interior.

11         How effectively is the Government working across departments and with local authorities to ensure a coordinated approach is taken to heat resilience?

11.1    In managing the increase of average temperatures, and the increasing frequency and intensity of heatwaves, it is imperative for Government departments to adopt a unified and collaborative approach towards heat resilience. Currently, Government focuses mainly on dealing with the impacts of heat events, when what is needed is a coordinated and collaborative approach to reduce overheating in the first place. This requires using a range of communication channels with infrastructure owners and local authorities.

12         Does the UK need a dedicated Heat Resilience Strategy? What lessons can be learned from other nations when it comes to national strategies for heat resilience?

12.1    A coordinated and collaboratively developed strategy that integrates urban planning, public health initiatives, infrastructure development and retrofit, and climate adaptation and resilience is crucial to effectively safeguarding communities against the adverse impacts of extreme heat. Key learnings from national strategies include:

• Collaboration with key public bodies
• Public communication for awareness and education
• Data-driven decision making and planning
• Long term policy integration

August 2023