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British Trimmings Extra Care Home

The project is for an Extra Care Home for elderly people with a range of support needs. The proposal comprises 87 self contained flats and a range of communal and public facilities. The primary aim for this study is to consider the effects of climate change on, and appropriate adaptation strategies for, elderly people in an extra care setting. In particular, how to ensure thermal comfort and safety for this vulnerable group. Other climate change factors relevant to the building and site such as site stability, flooding and water autonomy have been considered and integrated into the study and design solutions approached comprehensively. The study aims to provide a range of solutions that will be of direct use to this project now and in the future and to develop a toolkit methodology to guide client decision making on this and other projects.

Further project details

1. What approach did you take in assessing risks and identifying adaptation measures to mitigate the risks?

  • Analysis of future weather data
  • Review of heat related mortality studies
  • Psychrometric charts to assess cooling strategies
  • Comparative thermal modelling of existing proposals, alternative specifications and redesigns investigating effects of thermal mass, insulation, ventilation, shading, evaporative cooling and ground cooling
  • Twin approach of limited ‘adapted design’ and more radical ‘rationalised design’ including replaceable façade options
  • Focus on future-proofing where possible to avoid paying now for uncertain future scenarios Assessment of superstructure, foundations and site stability issues on designs
  • Calculation of site rainfall, flood risk, water autonomy requirements, and storage capacity
  • Design concept and appraisal of M&E systems to meet performance targets identified.

2. How have you communicated the risks and recommendations with your client? What methods worked well?

  • Client involvement in design team meetings from outset – essential for two way understanding
  • Interim review with client – to check priorities and commercial parameters
  • Summary presentation to client and local extra care interest group – clear visualisation/diagrams, characterisation of technical information rather than too many graphs and tables
  • Post study presentation feedback to full client development team.

3. What tools have you used to assess overheating and flood risks?

  • University of Exeter Prometheus: database of future climate models
  • IES software: thermal modelling
  • Climate Consultant 5.0: weather modelling including Psychrometric charts.

4. What has the client agreed to implement as a result of your adaptation work?

The client is very interested in the study and how it could be applied but has severe budgetary constraints as a public funded scheme. Clear benefits had to be demonstrated within a 30 year financial ‘horizon’ for the project and set against risks within that period or otherwise be no or low cost solutions.

Adaptations accepted had to be within the existing planning constraints. Significant recommendations agreed for implementation are:

  • thermal mass to attenuate temperatures and reduce overheating with brick and block with wet plaster finishes selected over timber frame
  • piled foundations extended to whole building to reduce risk of ground heave/shrinkage and allow closer proximity of shading trees
  • landscape redesigned to increase green spaces and shading for a cooling effect to the micro-climate and increased bio-diversity
  • integrated surface water attenuation and SUDs
  • linking of automated fire ventilation systems with ventilation for communal spaces and corridors
  • provision to split water distribution to allow for future rainwater recycling installation

The more adventurous ‘rationalised design’ options will not be adopted on this project but will inform the client’s briefing for future schemes, e.g. introducing enhanced performance criteria, decision ‘toolkit’ approach.

5. What were the major challenges so far in doing this adaptation work?

Difficult for sub-consultants to give a fixed service and price at the outset of an exploratory project. Relies a lot on flexibility and trust research took longer than anticipated and programme of work much less of a linear sequence than anticipated

Planning will not allow much visual difference from the approved scheme without requiring a new application

Difficult to get more than general cost advice on relative merits of design approaches until worked up. Life cycle costing very notional when including for new or future technologies and energy costs

Future energy saving payback periods were a low client priority since savings would largely benefit tenants not the client and therefore not ‘pay-back’ directly

Design and build process meant delivery team were not fully ‘on board’ with design thinking and various inconvenient adopted features were ignored or even omitted by agreement

Performance specifications and thermal modelling criteria were not properly understood by tendering contractors leading to problems with sequencing of detailed design information and costs.

6. What advice would you give others undertaking adaptation strategies?

  • Engage the client fully in the risk assessment process
  • Present risk and performance appraisals clearly to raise client awareness
  • Relate performance evaluation to the client’s economic ‘horizon’
  • Understand that the building must perform in response to ‘weather’ not ‘climate’
  • Understand that weather projections offer a range of possibilities and try to allow for future adaptability – ‘long life, loose fit’
  • Integrate design strategies as early as possible e.g. Water attenuation and landscape, orientation and shading, floor plans and ventilation routes
  • Specify enhanced performance standards against projected weather data for design and build contracts
  • Encourage continuity of approach with project delivery team.

British Trimmings care home plan