Local Authorities and Housing Associations

Recent advances in our understanding of how heat network function has now confirmed the reasons why historically they have performed so badly.

A measure of how badly is that no-one can really say. There have been no records kept of how a heat network functions over the years, and the difference between design efficiencies and delivered efficiencies is written of as almost a mystery, with installers been the most common bogey man, but other culprits been windows left open as a means of cooling.

Where heat meter data has been analysed on existing networks and compared to heat generation, efficiency figures as low as 50% are no surprise.

But now we know why. We have independent test data on most of the common HIU manufacturers, and we have calculation tools that work out the heat losses from pipework relative to energy used on hot water and central heating.

Using test data and calculation tools we can demonstrate exactly where the 50% (or more) losses go, and more importantly they establish beyond doubt a simple means to increase efficiency levels up to 85%.

Its Not Magic

Improving efficiency from 50% to 85% just by using the right HIUs seems too good to be true.

The following graph shows the results of recent tests carried out independently at the Swedish Institute of Technology, on many of the biggest makes of HIU. The height of the bars represents average annual network return temperatures (by volume), the width represents annual volumes used, and the area represents the volume of energy returning to the plant-room.

The difference in size between the bar on the left, a typical HIU in London, and the bar on the right, the best modern HIU, is startling. The difference been that historically, one hundred times as much energy is been returned to the plant-rooms over a year than needs to be.