We take an intensely client-focused approach to our work, and have been very successful at creating and releasing asset value for our clients, often in difficult, challenging circumstances. Since its founding in 1983, the Practice has focused on finding ways of meeting human demands on land which conserve rather than exploit the earth's natural resources. This is the essence of sustainable development.

In practice, this is reflected in four inter-related themes:

• making our towns and cities healthy and attractive
• finding effective ways of recycling previously used land and buildings
• reducing energy use and pollution in our buildings and transport systems
• conserving both our natural and cultural heritage

To achieve these goals we take a broadly based, creative approach to problem solving. Since 1983 we have developed and applied a range of multi-disciplinary skills to a wide range of projects throughout the UK and internationally. Over 700 projects have been successfully completed for over 100 clients in both public and private sectors.

The concept of sustainability is not new. Almost two thousand years ago, Vitruvius defined the principles of good design as "commodity, firmness and delight". At a time when sustainability is being used by almost anybody to justify almost anything, these principles serve us well in the search for solutions which are truly sustainable:

• "Commodity" - does it function efficiently?
• "Firmness" - will it last?
• "Delight" - does it please and satisfy those who use it?

Our modern world has new concerns , such as global warming, depletion of the earth's natural resources and eco-systems, the need to regenerate traditional industrial and urban areas, and the impact of these on human well being.

Sustainable economies need long-term profitability and strong markets. At the same time assets have to be used efficiently, the earth's natural resources have to be conserved, damage to the environment has to be prevented or repaired, and communities have to be able to prosper. Since 1983, Cass Associates has been providing its clients with the kind of long term, joined up thinking which is essential if these aspirations are to be met.

Sustainability is about having confidence in the future, and our work provides clear, hard evidence of how it can be achieved in practice. A selection of projects from over 700 carried out since 1983 provides an insight into our approach. They demonstrate the wide-ranging nature of our output - both in terms of our clients and the range of creative and technical skills involved. Our work is sometimes difficult to categorise conventionally, as it often cuts across traditional professional and technical boundaries. At Cass Associates, this is regarded as an essential component of "Sustainability by Design".