All posts by Editor

Energy technologies, Human factors

Duty-standby rotation

One of my clients, who operates computer data centres, asked his monitoring and targeting software supplier to conduct some pilot analyses using daily data. Cusum analysis of one particular circuit, which was feeding computer-room air cooling (CRAC) units, threw up an interesting observation: energy performance had been toggling between good and bad on the first of every month. This fact had been masked by the weather and variations in the quantity of energy consumed in the equipment racks, but once revealed, it was traced to the fact that they were alternating two banks of CRACs on a monthly cycle. In situations like this, it pays to change the regime so that preference is given to the more energy-efficient plant. This has the secondary advantage that the standby set will have more maintenance life left in it when the lead set fails. Cusum analysis is very good at providing insights like this, which is why I give it prominence in my training courses on monitoring and targeting.

The other place one finds opportunities for instant savings is multi-boiler heating systems, where, too often, the firing sequence is deliberately rotated to give each boiler the lead and even out the wear. Apart from making no sense in terms of risk management (when one fails, all the survivors will be equally clapped-out) it also misses the opportunity to favour the unit with the highest combustion efficiency, and thereby consume less fuel for a given output of useful heat. Anyone unfamiliar with combustion efficiency and the opportunities that it offers can read up in the A to Z guide at www.vesma.com.

Combustion tuning is a good (and frequently-overlooked) opportunity for nearly all fuel users.

Link: Energy management training

April fools

Case history of the month

DATELINE 1 APRIL 2014: “How green can you be?” is the message from major energy users Gulley Bull Ltd, who undertook a multi-faceted approach to saving fuel in their head office. They combined magnetic fuel conditioning, which offered a 20% saving, with two kinds of boiler water treatment. One, a simple cartridge containing special stones developed by a NASA scientist, changes a property of water to improve heat transfer by 25%. The other is a patented secret additive which prevents large steam bubbles forming in the boiler and also improves efficiency by 25%. Their building had solid walls, and was hard to insulate, but their energy manager’s researches uncovered a paint additive containing ceramic microspheres which, because they contain a vacuum, act as perfect insulators and promised a 30% saving on their heating costs just from redecorating the offices. Finally, they replaced their heating timeswitch with a control which claims to cuts fuel use by 16% by intermittently turning off the heating, saving fuel without sacrificing comfort: “an ingenious idea which took our total fuel savings to 116%” according to Gulley Bull spokeswoman April Fulstryk.

Bogus claims, Energy technologies

Super-thin insulation

Super-thin thermal insulation is in my sights at the moment. There are two categories: (a) multi-layer foil and fibre; and (b) paints or paint additives. The insulating effect of multi-layer systems is basically equal to the same thickness of whatever insulating fibre they use, but there is some additional advantage where they are installed with an air gap either side, since they create an extra cavity which has a certain thermal resistance. Their reflective foil will impart additional thermal resistance by preventing radiation from the hot to the cold face of the cavity. But note, however, that after filling with ordinary fibre, the hot and cold surfaces of the cavity can no longer see each other, and heat transfer is solely by conduction. So BOTH techniques eliminate radiative transfer across the cavity and the foil therefore imparts no advantage.

Insulating paints meanwhile, even if composed of material with high thermal resistivity, will have totally negligible effect because the insulating layer is microscopically thin (under 0.3mm by my calculations, based on coverage data in the advertisements). Claims that their ingredients reflect heat are unsound because those so-say reflective materials are buried in the paint layer; to reflect heat the SURFACE of the paint would need to act like a mirror to infra-red radiation.

Link: Energy management training