Located in the London Borough of Hounslow, Westbrook Primary School provides education to primary school students aged 3 to 11 years. The project includes the demolition of the existing facility and the erection of new school buildings at an alternative location on the site. A main challenge of the site is its location under the Heathrow flight path and the acoustic issues it presents to natural ventilation and energy efficiency requirements. One solution employed by the project is the use of a thermal labyrinth. The labyrinth is used to provide outside air that has been thermally modulated by the earth rather than actively conditioned, giving potential energy and acoustic benefits and an intrinsic long-term resilience to the effects of climate change.
Further project details
1. What approach did you take in assessing risks and identifying adaptation measures to mitigate the risks?
Risks were assessed using a rating of probability and impact resulting in a rating between low and extreme.
Where possible risks were quantified in terms of their effect on the building under different climate scenarios.
Some adaptation ideas were generated at the CCA focus session held with the client and design team early in the process. More ideas were generated as the project progressed by the CCA team.
2. How have you communicated the risks and recommendations with your client? What methods worked well?
Risks and recommendations were communicated to the client using a combination of text, graphics and numerical data in presentation and discussion settings and more formally in printed reports.
The most mutually beneficial interactions were roundtable discussions of the issues, implications and likely solutions to the problem. The complexity, uniqueness and originality of the climate change risks meant that the pertinent issues can be lost in the weight of data and explanation.
3. What tools have you used to assess overheating and flood risks?
To assess comfort we have used TAS modelling software with future weather files provided by the Prometheus project at the University of Exeter.
Assessing flooding issues EPA flood map resources and the Environment Agency’s guidelines documents, BS 8515:2009, the RainCycle calculator for rainfall harvesting (WaterScan), Building Greener for guidance on green roofs (Early et al, 2007) Win-Des MicroDrainage for site drainage calculations and UKCP09 rainfall data.
Construction risks were assessed and informed by UKCP09 wind and rainfall data, the site investigation report, the Eurocodes (BS EN 1990, 1991) and BS8104:1992.
4. What has the client agreed to implement as a result of your adaptation work?
The client has agreed to all proposed modifications pending the cost impact as provided by the competitive tender. Specifically, the following has been noted as part of the tender package addenda:
- widening of the earth tubes
- provision of structural fixing points to allow ease of shading retrofit in future
- planting of additional trees
- provision of an extensive green roof on flat roof locations.
- rainwater collection from central pitched roof location and reuse in toilet flushing.
5. What were the major challenges so far in doing this adaptation work?
So far the adaptation work has run smoothly. We believe to realise value for the client there needs to be an emphasis on being able to quantify the impact of climate change scenarios to understand whether immediate or delayed investment is necessary. This can be done with some degree of certainty for most risks however some construction and water risks require further technical support to enable quantification and enable confident decision making.
6. What advice would you give others undertaking adaptation strategies?
Where possible, the use of thermal labyrinths are a great way of smoothing out the extreme effects of climate change in a passive way. This is a strategy that is intrinsically very resistant to the temperature effects of climate change.
