Not too hot

Ninety percent of heating and ventilation control systems in buildings are inadequate, costing business £500m/year in additional energy costs, UK research tells us. The reasons for the problems are varied, and solutions not necessarily simple. Julian Miller of AEC, which is marketing a software tool that identifies routes to efficient control with the aim of saving money and emissions, says the problems can sometimes be simple. He recalls a site where chillers were running 24-hours on Christmas Day. “I think the company was spending about £100,000/year on electricity,” he says.

However, this is a rather extreme example, and there are any number of factors that chip away at the efficiency of a building’s heating system, ranging from boiler efficiency itself to interference from untrained occupants.

Roger Hitchin of BRE gives an example of just how fraught the subject can be: “Heating systems – particularly multi-boiler systems – are designed as the engineer thinks they are going to be operated,” he says. “But as time goes on and people come and go in the building, the boilerhouse, settings, and the controls are left on inappropriate values or people fiddle with them to deal with a specific problem who don’t really understand what they are doing.”

Smaller sites

Large sites with substantial energy bills will probably employ a building manager – although the level of expertise in running boilers he or she may have is moot. But as Hitchin says: “As you come down the scale to the more typical smaller installation, which are very numerous but aren’t seen as justifying that kind of hands-on management, that’s where you’ll find the real problem lies.”

Action Energy is an energy efficiency programme run by the Carbon Trust, which advises business on ways of reducing energy use. Part of the service it provides is site visits by energy consultants to help companies identify potential savings. Working with BRE, these site visits have been used to assess AEC’s software, which evaluates the adequacy of boiler plant control systems. Results so far have been positive, and Chris Burgess of the Alpha Energy Consultancy says: The analysis software is robust and the results help us to back up recommendations on control improvements.”

What AEC has done is to develop a series of algorithms to analyse data on boiler performance, pinpointing

inefficiencies. “It amounts to a huge amount of common sense wrapped up in a lot of maths,” Miller says.

Performance analysis

Fixed information such as the number and power rating of the boilers, fuel spend and consumption, days and hours of occupancy, and the presence or absence of combined heat and power are fed into the system.

AEC uses data logging equipment to gather key temperatures over a 24-hour period at 1min intervals on:

• Common flow & return;

• Individual boiler flow temperatures;

• Zone flow and return;

• DHW secondary;

• Space; and

• Outside air.

“One-minute data gives a accurate picture of what’s going on – you don’t miss whole boiler firing cycles,” Miller says.

This information, together with details of building occupancy and boiler sizings, are run through the software, which is able to analyse the data from an efficiency perspective broken into specific areas:

• Time related; matching occupancy to provision of target space temperature;

• Overheating of primary, ensuring heat provided is not being returned;

• Boiler sequencing – ensuring that boilers only fire when a specific demand has been identified;

• Zone control – examining the compensation algorithms against space and external temperate to ensure optimum efficiency; and

• Domestic hot water adequacy; alerting to the potential hazards of scalding and Legionella.

This information is collated, confirming whether the controls are appropriate and identifying where improvements can be made. An efficiency report is then produced.

The software can indicate where savings are available and their scale, as well as presenting options for efficiency improvements.

Efficiency issues

The true value of the software is that it provides such an accurate overall picture of heating system performance. Miller says: “Your boiler may be incredibly efficient, but if it is firing 24-hours and the building is only occupied from nine to five, then the process itself is inefficient.”

But problems will undoubtedly exist on a micro-level, due to poor boiler sequencing, heat losses in the pipework, faulty valves and so on. And even if a sophisticated building energy management system is in place, there is no guarantee that the system is efficient. “A lot of building energy management systems don’t deliver the savings or efficiencies that they should, simply because people aren’t quite sure how to set them up properly – or how to use them,” Hitchin says.

Miller is confident that AEC can deliver concrete efficiency improvements at almost any site. “On the worst site we investigated, we found opportunities for over 70% improvements. And in about 50% of the buildings we see, the owners could make 20-30% savings.”

Miller says companies will find the process financially worthwhile. “We would be very surprised if there was any building with a fuel spend of over £20,000/year that we could not achieve a sub 12-month payback.”

Substantial savings

If that in itself is not motivation enough, the ravages of the Climate Change Levy provide a further impetus to seek reductions in energy use.

Furthermore, the government has identified energy efficiency as a key plank of its strategy for reaching emissions reduction targets, suggesting businesses will come under more regulatory pressure to make improvements. Hitchin says: “There are very substantial savings to be made by relatively straightforward adjustments in boilerhouses.”

But whether companies hire a company like AEC or use the services of Action Energy – as 3,600 companies did in the past financial year – identifying where efficiencies gains can be made is not enough.

Neville Wilson of Action Energy makes it clear: “Opportunities don’t equal carbon emission reductions until they are actually implemented. It is like funny money until it is actually in the warehouse.”