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How to design green controls that work

Energy is big news just now. The recent devastating oil spill in the Gulf of Mexico and the associated loss of human life hogged headlines and threatened all our pension savings.

We have suddenly had a brief insight into the incredible technology and risks involved in extracting oil from more than a mile beneath the sea.

The stored energy from these ancient compressed plants remains is the elixir of modern life. Oil frees us to travel the world and makes us richer than any previous generations.

However, warning signals abound. Peak oil is near and gets closer as billions in the developing world demand similar standards of living to us, while combustion gases from burning stored carbon are changing the climate with potentially catastrophic effects.

Furthermore, tanker drivers’ strikes and the cold snap last winter remind us how completely we depend on hydrocarbons for transport, heat and power.

What are the solutions?

Thirty per cent of energy is used in buildings. Windmills and photocells will help, but how we control energy use more efficiently while providing comfortable and productive environments is the greatest challenge for building engineers. It is also critical to our personal safety, economy and lifestyles.

Engineering building services is all about using energy to provide comfortable and productive indoor environments.

We start with ‘design conditions’, eg 32 deg C 50 per cent humidity and -4 deg C 100 per cent humidity for the UK. We size our plant to make sure we can maintain the target conditions of, say, 21 deg 40-60 per cent RH in all circumstances.

This means making sure the chillers, pumps and fans can deliver enough water and cool air to compensate for worst case heat gain from occupants, equipment and sun. In winter, the boilers, pumps and heating equipment must keep the occupants warm.

The thing is that these design conditions rarely occur. Normally the building exists in weather conditions somewhere in between these extreme states. This is the proper domain of the controls engineer.

We must ensure sure that a building controls effectively at ‘part load’. That depends on good design, good installation and good operation and maintenance.

Sadly, this is rarely achieved, but improvements can be made by starting the systems design with consideration of how the services will perform in part-load conditions, keeping things simple wherever possible, specifying a building management system and insisting on good quality human interfaces and graphics for non-technical users.

It is also beneficial to produce software and graphics early and test as much as possible off site, as well as pre-commissioning thoroughly then commissioning and testing thoroughly, crediting the validation checks to individuals, providing good quality training and maintaining, and tuning and retuning controls continuously with the building occupied.

Peter McDermott is a building integration consultant at Buro Happold