Energy consumption in buildings tends to get less attention than production inputs because it involves less money overall, says Alan Aldridge of the Energy Services and Technology Association.
Product sale-price and company profitability depend upon minimising input costs, while maintaining quality and maximising profit.
The ancillaries, such as building operating costs, administration, sales and marketing, etc, tend to be viewed as overheads which have to be accepted and factored in.
Yet there is no reason why this should be the case. All operating costs and all purchases should be scrutinised – and all resources should be used as efficiently as possible. Without that, a business will haemorrhage money. In the case of energy, several factors combine to increase the overall cost to business.
First, there is the volatility from geo-political instability. While this may be temporary, the number of incidents over recent years has meant that energy prices have been very variable. Second, demand is rising across the world. The International Energy Agency forecasts that demand will increase by 40% by 2030 and that must increase prices. Third, the government has stiff carbon reduction targets to meet under both UK legislation and international agreements, so will be looking to persuade consumers of all sizes to cut consumption of fossil fuels.
Heavy industry already has to cope with paying for emissions allowances and now other large users will have to pay £12 for every tonne of carbon emitted under the CRC Energy Efficiency Scheme.
Under the Electricity Markets Review currently being undertaken by the Government, a ‘floor price’ for carbon will be introduced. This will mean that a minimum price for carbon emissions can be set. The reason is to make investment in low carbon energy supply more commercially viable: for consumers it can only mean higher bills.
So reducing fossil-fuel based energy consumption (including grid-supplied electricity) is key to reducing costs and to reducing emissions. There are two ways of doing this: reducing demand or switching to low carbon energy. Much has been made of on-site renewables but the current review of Feed-In-Tariffs (FITs) shows that Government policy on this issue is still in flux. The basis of FITs is to provide a return of around 8% per year.
Many energy efficiency projects will deliver a much higher return than this, so reducing demand through effective energy management is a clear priority and has a proven record. Reducing demand automatically cuts emissions, regardless of energy source, and lowers exposure to carbon allowance costs.
Now, while some of the newer industries boast brand-new state-of-the-art construction, many more traditional sectors have, typically, buildings that are several decades old. The energy performance standards of structures even 15 years old will be much poorer than that of one built today.
The likelihood is that there will be significant opportunities to make savings on energy through simple improvements. These will not just be increasing insulation levels and draughtproofing doors and windows, important though these are. Too many people forget that low-energy lighting that is switched on unnecessarily is still wasting energy. Energy consumption must be controlled and managed if costs and emissions are to be minimised.
Figure 1: Performance drift
Automatic Monitoring and Targeting
The framework for effective energy management is the technique of Monitoring & Targeting. The maxim “You can’t manage what you can’t measure” is commonly attributed to the 19th century scientist Lord Kelvin, but it still holds true today. However, the tedious collection and manual inputting of meter data has long passed. Automatic Monitoring & Targeting (aM&T) systems are now wellestablished and the reports they generate can be fed into standard administration, estates and financial packages used by business. Their effectiveness is recognised by the Government as their installation qualifies for an allowance against carbon targets in the Building Regulations.
With the use of aM&T, areas where energy is being wasted can be quickly highlighted – and addressed. If the building is using electricity at the weekend when there is no production or maintenance going on, then there is potentially a problem with the control system. Issues such as jammed switches on heaters, lighting always on in storage cupboards (out of anyone’s sight) show up quite quickly.
Using Degree Day monitoring, it can be seen when a building is using too much energy compared to historical performance – or compared to other buildings of this type. This can also be used to capture the effect of ‘performance drift’ over time (see Figure 1).
Some of the simplest measures to tackle excessive energy use (and carbon emissions) involve checking set-points and time switches. If the latter do not automatically switch over in spring and autumn for example, the heating will come on too soon or switch off too late.
Air conditioning and heating system setpoints need to be checked regularly. If these overlap, then both can operate simultaneously, working against each other and pushing up the bills. The Building Regulations now require zoning controls, so that areas near windows, say, where there is significant solar gain during summer (and heat loss during winter) have different control strategies from areas in the core of the building where environmental conditions are more constant.
Variable speed drives (VSDs or inverters) are commonly used on production machinery to optimise partload working, and they are available for air conditioning systems and pumped water systems as well which often have to operate at variable loads.
Figure 2: aM&T systems can be used to target wastage and optimise consumption
As an example of the opportunities from individual technologies, take one area where ESTA has found there are substantial opportunities for energy savings, that of lighting. First of course antiquated conventional tungsten filament lighting should be replaced with low energy alternatives. But there are now low-energy options for fluorescent lighting too. In areas where desk working requires good lighting level for detailed work, individual task lamps may be appropriate with control left to the individual, with lower general lighting levels for walkways and communal areas.
As mentioned earlier, though, lowenergy lighting on its own will not deliver the best results. There needs to be a control strategy or management system.
So all the lighting should have a default switch off after everyone has gone home (although individual lamps can have a manual override if people are working late). Daylight sensors which make use of natural lighting conditions can cut artificial lighting. Areas which are only periodically used like storage areas, conference rooms and washrooms can be fitted with occupancy sensors to automatically switch lights on and off. The latest edition of the Part L Building Regulations is based on the model of having presence detection and daylight dimming in virtually all areas above 30m2.
There are always opportunities for improving energy efficiency. Even where programmes have been implemented in the past, energy management is always developing and new, more costeffective solutions are continually being developed. The integration of aM&T with financial software packages should make it easier to identify and quantify the potential savings in a manner that can be used to convince senior management of the benefits.
Figure 3: VSDs can reduce energy consumption on air conditioning systems working at part-load