Sustainable Design and Construction

By Cindy Harris, Head of Design Review, Design Commission for Wales

Design and construction are essential parts of the same exercise – to create a building or streetscape or townscape. While different professions each have their own part to play, the best projects result from both partners working together from an early stage.

This is especially true when it comes to sustainable construction – measures which are necessary to ensure energy efficient, low carbon buildings need to be taken at the earliest possible stage of the design process for maximum impact and practical cost effectiveness.

Similarly, aspects of construction and ‘buildability’ will affect the design development and the particular materials and technologies specified. These early decisions will drive key aspects of the project and maximise the best sustainable solutions.

Over half the UK’s carbon emissions are generated by the construction and servicing of buildings, so the energy performance of new and existing buildings is crucial to meeting our national commitments and international obligations.

Energy efficient homes offer greater levels of comfort for the occupier and will be cheaper to run and maintain. The social importance of reducing fuel poverty, together with the need to protect the security of fuel supply in the future and to limit the impact of climate change, all combine to deliver a powerful argument in favour of reducing energy use in buildings. This in turn has a direct effect on bringing down carbon emissions.

At the level of the individual building, the designer, contractor and specialist consultants all need to join forces along with the client to deliver low carbon buildings.

All new housing in Wales now has to achieve Level 3 of the Code for Sustainable Homes as a minimum, together with a 31% reduction in CO2 levels compared with 2006. The means of achieving this should be set out in the Design and Access Statements accompanying new planning applications. Used properly they are a powerful tool and should not be reduced to a tick box exercise.

Designers and developers should observe the ‘energy hierarchy’ whereby the easiest and most cost effective carbon savings are made first, usually built into the fabric of the building.

These measures are often very simple and cost little to achieve when considered early. They include high levels of insulation to stop heat escaping in the winter and to keep buildings cool in the summer. Equally important is the elimination of uncontrolled ‘draughts’, together with controlled ventilation directed when and where it is needed.

The orientation of the building on the site, and the size and location of windows and other glazed areas should be arranged to take full advantage day light and of the sun’s energy – which is both free and renewable. A ‘passive solar’ approach to building design uses solar energy to pre-heat the building elements and incoming air, as well as introducing high levels of daylight into the building and reducing use of electric lights.

Once these basic steps have been incorporated, consideration can be given to appropriate renewable technologies which work well at the level of a single building, such as solar water heating, which should meet at least 50% of domestic hot water demand over the course of a year.

The choice of building materials also has a significant environmental impact. Ideally we should be choosing renewable materials, sustainably produced and genuinely locally sourced, with minimal processing and transportation. Low ‘embodied energy’ materials are preferred – this refers to the energy consumed (and CO2 emitted) during the production process and throughout the building’s life.

Increasingly we are seeing the use of ultra-low-impact building materials, such as timber poles, straw bales and unfired clay bricks, hemp and lime, to construct mainstream, modern, comfortable and energy-efficient houses that have a low ‘embodied energy’.

Of course, any process of construction is designed to change the environment, and is bound to cause some environmental degradation. Sometimes we have to weigh different impacts against each other – for instance choosing a very energy efficient window or organic paint, which needs to be transported over long distances. In the end, we may have to trade off certain impacts against products or processes that are even more damaging.

An environmentally sound building must also be people-friendly. This means a structure which is flexible and easily adaptable, so that it can respond to the changing demands on its function, layout and technical performance.

Too often the benefits of low carbon technologies are not realised in practice because users do not understand how they should operate. Owners and tenants should be encouraged to use them as they are designed – just as they use any other piece of equipment – their smart phone or car for instance. Most building technologies are very simply and their proper use means that the building performs as it should – put simply, it will ‘do what it says on the tin’.

Sustainability is one of those all-encompassing terms, and if a development is to be truly sustainable it should address the environmental aspects of construction on several levels.

At the global level, we should be aware of the impact of mining and processing materials in other parts of the world, both in terms of resource depletion and the health and wellbeing of local populations and ecosystems. CO2 pollution likewise has a global impact.

At the local level, we can help to lay the basis of sustainable communities by supporting mixed use developments with a good mix of daytime and evening uses and attractive, well used public spaces.

A reasonably high density of development, particularly in towns and cities, can trigger and help support the development of community infrastructure such as shops, schools, libraries and health centres, as well as good public transport.

Good guidance on street design and residential layout for local planning authorities is provided in the Manual for Streets. This important document reinterprets the function of residential streets, away from being mainly traffic routes and towards more sociable uses. Streets are designed to give pedestrians and cyclists greater priority and to ensure that vehicles travel at restricted speeds with a greater awareness of other road users.

With greater densities comes the increased responsibility on the developer and local planning authority, to ensure excellent quality in the buildings and public spaces – without this care, the schemes will become the slums of tomorrow with costly social and environmental consequences.

The creation of good public spaces serving the needs of the local community is about more than just a collection of architecture or low carbon buildings. Such places are memorable and distinctive, well used and cherished by the people who live or work in the area, and appreciated by those who are just passing through.

They will be easy to find and recognise, they will encourage people to linger and socialise by providing attractive and sheltered gathering spaces, and they will be well designed with appropriate planting and high quality materials. As assets for the community they will also be well looked after and maintained, and can help to foster a sense of pride and ownership. They will be loved and will last.