Retrofitting

Retrofitting is the term used to describe the fitting of climate adaptation measures to existing premises. It is likely to be most cost-effective as an integral part of major maintenance or refurbishment programmes, however, there may be instances where risks are such that ad hoc retrofits need to be considered. In either case the aim should be that all major retrofits have design lifetimes appropriate to the investment involved, taking into account site specific issues and projected climate changes over the period for your locality. Typically this is likely to be in the range of 10 to 30 years.

The two most significant risks to premises are likely to be flooding and overheating, but refurbishment projects should aim to take account of all threats and opportunities arising from climate changes over their design lifetime. Generally, specifying effective retrofitting measures will require specialist knowledge. Therefore, if the project is being undertaken by an in-house team it will be important to ensure that sufficient technical knowledge is available, or that advice is sought from suitably qualified professionals, such as building services engineers. If the work is being contracted out, the requirement for premises to be well-adapted to climate change should be clearly specified as part of the tender brief for architects and contractors. Some examples of potential retrofitting options are suggested below:

Flooding:

Auditing of present capacity of both on and off site rainwater systems to ensure that they can cope with projected increases in the frequency and intensity of rainfall. In the light of this audit, retrofitting options could include:

• Upsizing of gutters, down pipes, etc. to cope with more intense rainfall
• The use of green roofs to lessen the rate of runoff from large roof areas - green roofs can be considered as win-win adaptations because the have the potential to offer multiple benefits.
• Use of SUDS techniques to manage on site water and minimise off site impacts from runoff
• Reduction in the extent of impermeable surfaces on site by use of permeable materials for roads, paths, parking areas, etc.
• Use of local flood defence measures to minimise risks of flooding to premises
• Locating all electrical systems to minimise risks in the event of flooding
• Ensuring that the use of areas within the premises and location of equipment minimises risks in the event of flooding

Overheating:

Reviewing the solar gain from glazing taking account of seasonal and daily changes to sun angles - win-win approaches should aim to maximise solar gain during cooler seasons and minimise gain during the summer. Possible adaptations could include:

• Changes to the size and position of glazed areas
• The use of roof overhangs, external shading, or brise-soleil to minimise solar gain at high sun angles.
• The use of smart glazing materials and automated shading systems
• Planting schemes to give increased shade

Improving insulation to reduce transmission of high external temperatures to interior spaces. This is potentially a win-win approach with reducing winter heating requirements, but needs to be treated with care. Poorly designed insulation can exacerbate overheating if it limits opportunities for cooling during periods of excessive heat particularly where light-weight materials are used for reasons of cost. Buildings with high thermal mass tend to perform better in high temperatures than lighter weight structures so, ideally, the aim should be to combine appropriate insulation with high thermal mass.

Utilising opportunities for passive cooling

The use of light-coloured and reflective surfaces for walls and roofs to minimise radiant gain.

The use of green walls and climbing plants on external walls to produce shade and evaporative cooling.

Water stress and conservation

Changes to the extent and pattern of rainfall is likely to exacerbate problems of water stress, particularly in southern and eastern areas of the country where this is already an issue. Refurbishment projects offer opportunities to conserve water including:

• Fitting of low-flow taps and shower heads
• Fitting of ultra low flush or variable flush toilets
• Installing rain water harvesting and grey water recycling for non-potable uses
• Changes to landscaping and planting schemes to minimise watering requirements

Opportunities

Ground source heat pumps are an energy efficient means of heating and cooling, but require extensive groundwork for installation and large internal radiating surfaces, typically floors, to convey heat, and hence are difficult to retrofit. However, there may be cost-effective opportunities for installation on more major refurbishment projects if these include groundwork and significant structural work for other purposes.

Sources of advice

The Three Regions Climate Change Group's report Retrofitting Existing Homes for Climate Change Impact offers guidance and case studies on retrofitting different types of houses to adapt to flooding, water stress and overheating.

There is very little other advice specifically on retrofitting adaptation measures, but the following offer guidance that may also be useful for retrofitting projects:

Adapting to climate change: a checklist for development
Adapting to Climate Change: A Case Study Companion to the Checklist for Development

UKCIP guidance on Adaptation responses in the build environment

TCPA publication Adapting to climate change by design

NHBC Foundation Climate Change and Innovation in House Building: Designing out Risk.
Urban Design (Spring 2007, Issues 102) focuses on the topic of adapting to climate change.
The National Centre for Excellence in Housing provides some guidance on sustainable housing, although here is little specifically about adaptation to climate change.

Examples