Energy Reduction in Buildings: A Measured Approach

Published by Lucy Blackwell for Stroma in Housing and also in Education, Environment

Unbalanced Demand
This winter saw an unprecedented peak in energy demand and, for the first time, industrial companies on interruptible contracts were forced “off grid” as the energy companies struggled to balance supply and demand. Unfortunately this situation is widely expected to be repeated. An ever rising demand for energy, coupled with increased reliance upon fuel supplied from overseas along with the planned decommissioning of coal fired power stations over the next five years with their nuclear replacements not due on line until 2016 has heightened tensions in the UK energy market.

According to the industry regulator, Ofgem, a £200bn investment is needed over the next 10 years to resurrect the UK’s beleaguered energy infrastructure. This sum is likely to be recouped in the short term by an estimated 35-40 percent rise in energy prices; the brunt of which will be sorely felt by SME businesses. In light of this bleak forecast, now is the time for companies to reduce their energy requirements and in doing so lower their utility costs and eradicate the risk of them literally conducting commerce in the dark.

Carbon SavingsThe Carbon Vs Cost Conundrum
There is a degree of energy waste within all buildings and businesses. Combating the causes of this waste is the most tangible way of decreasing energy reliance and protecting the bottom line. The recent trend has been to seek the solution through the purchase of costly renewable technology. However covering roofs with solar panels or installing ground source heat pumps is of limited energy saving benefit if the building cannot retain heat.

The discussion and setting of targets measured in terms of carbon emissions has served to muddy the issue. For example, exchanging fuel types for one that is ‘cleaner’, less carbon intensive, will reduce the emissions of a business. However this often requires large capital investment and doesn’t always result in a lower cost of running. For example in a typical heating system, if the buildings demand for heat remains the same and if neither the unit cost of the input energy has been reduced nor an increase the efficiency of converting the input energy into the heat output has been realised, then the over all running cost will not be reduced. Conversely, by initially reducing the heat output demand the input energy and it’s associated carbon emissions and running costs are both immediately reduced. Additionally, the size of any HVAC plant required will be reduced, and it’s life prolonged. The natural progression is then to review the technologies delivering energy into or generating energy for the building, in order to ascertain whether a more adept, low-carbon system could be utilised.

From New build to Retrofit
The UK government has pledged to reduce carbon emissions by 80 percent by 2050. The strategy to realise this improvement initially focused on the new build environment where compliance could be used to drive change through the building and planning. However, as it is estimated that around 75 percent of the building stock of 2050 is already in existence, the emphasis must shift from new build to the improvement of existing buildings. The government has already embarked on it’s agenda through initiatives such as the retrofit of social housing and the clean energy cashback scheme. In the commercial sector the inception of the ‘Carbon Reduction Commitment Energy Efficiency Scheme’ (CRC) this year is a further example. Although initially only effecting a minority of the larger companies, the CRC is a clear indication of industry’s energy future.

It is important that as the emphasis swings from new build to existing buildings and that technology and construction techniques developed in the New-Build sector are understood and adapted to improve existing buildings.

Focus on Waste reduction
It is commonly accepted among industry professionals that whilst any energy efficiency strategy is bespoke to the requirements of an individual building, three underlying concepts remain constant. These are:

* The identification and reduction of energy waste
* The optimisation of energy use through improved control
* An improved provision of energy via more efficient technology

The primary focus for any business must be to reduce waste. One of the most economical methods of ensuring the sustainable performance of a building is to look at its construction and fabric. By making simple and relatively low-cost fabric improvements, a permanent reduction in space heating and cooling energy can be achieved. Subsequently, this will lead to significant energy and monetary savings.

The building’s envelope is the barrier that ideally retains heat energy in winter (or keeps it out in summer). In poorly functioning envelopes, heating/cooling energy will be lost to the atmosphere at a higher rate than the loss from efficient envelopes. This energy will mainly flow through the envelope through conduction and/or convection. Conduction occurs because heat will naturally flow from hot to cold areas, even through the building envelope. An insulation layer will reduce this by virtue of its very low heat conductivity. Convection can occur where there is a disparity in air pressure Office Blockdifferences across the envelope. In buildings with ‘leaky’ envelopes, air will flow either into or out of the building, driven by wind or temperature (and therefore pressure) difference.

It is key to remember that a well insulated building may still suffer energy losses via convection, most commonly referred to as ‘air leakage’. Generally speaking these improvements can be made for relatively low capital cost and as the benefit of the reduction in terms of CO2 emissions and energy usage will be realised over the lifetime of the building the total saving can be extremely high. What’s more, reducing waste prior to investing in renewable or other such capital intensive equipment has the compound effect of reducing the investment required for such technology.

The New-Build sector have recognized the importance of convection, imposing a minimum figure for air permeability in the Building Regulations. All constructions must achieve a minimum air permeability rate of 10m³/hr.m² @ 50 Pa. For a typical building this minimum standard can be visualised as a hole the size of a twenty-pence piece in every square meter of external fabric and is estimated to result in a loss of typically 20 percent in purchased space heat energy. It goes without saying that achieving a level beyond simple compliance will significantly improve the energy performance of a building.

Air sealing is a technique which is not only valuable in the new build sector. It can readily be applied to existing buildings. In fact in some building constructions air sealing can even be more appropriate improvement than insulation.

The Isle of Man department of education have as part of an over arching review of their building stock included a test of the premises’ air permeability. Cronk-y-berry Primary School was found to have an air-leakage rate three times higher than the current minimum building regulations. Following a programme of remedial works, a 57 percent improvement in air permeability rate was achieved. This translated into a 30percent reduction in space heating load, and a 44 tonne reduction in CO2 emissions and an estimated utility saving of £9,000 per annum. Delighted with the results, the Client is now assessing the potential of air source heat pump technology, in order to further improve the school’s energy performance

Conclusion
The challenges facing the UK SME market in terms of energy use should not be ignored. Against a back drop of increasing prices and dwindling supplies, those companies who can decrease their energy demand will see a tangible decrease in their running costs and increase in their profitability. However, the solution employed must be carefully thought through to ensure that maximum running cost improvements are achieved for the lowest capital investment.

For further information, call 0845 621 11 11 or email info@stroma.com. Alternatively, visit www.stroma.com for details of Stroma’s service offering.