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In 2012, the NHS carbon footprint represented 40 per cent of public sector emissions. Building energy use accounts for 17 per cent of this figure, with a cost of £636M. Of this, electricity accounts for slightly more than 50 per cent of the emissions, which continue to rise whilst fossil fuel use is falling.
Overall the building emissions trend is downwards. The decline in fossil energy emissions is indicative of better insulated, more airtight buildings with heating plant that has a higher seasonal efficiency and less steam use. Electricity use reductions have been achieved through more efficient: motors, mechanical ventilation and cooling systems and lighting. But electrical savings have been offset by an increase in medical and IT equipment, and increased patient numbers indicating that decarbonising electrical consumption is essential to achieve further significant carbon emissions from the NHS Estate.
Analysis undertaken for DoH a few years ago by BRE, indicated that the emissions of average existing hospitals was 145KgCO2/m2 and that potentially this could be deduced to 110KgCO2/m2 if all good and best practice energy measures were applied; a potential saving of almost 25 per cent. Other analysis we undertook of smaller non-acute buildings, where the level of energy management tends to be lower, suggested that potential here for savings could average 35 per cent. This analysis did not include opportunities through low and zero carbon technologies.
So how can these savings be achieved? Reducing energy consumption requires a combination of good housekeeping, effective energy management of existing systems, investing in newer more efficient technologies and using low/zero carbon energy sources. Getting a better understanding of the performance of your buildings through measurement, surveys or modeling is an essential part of this process.
Effective metering is also essential: If you can’t measure it you can’t manage it. Identifying and delivering savings requires energy consumption to be measured.
An effective automated meter reading system will provide graphical outputs on systems, departments and individual items of plant to identify where energy is being used to enable consumption to be compared with benchmarks to help identify saving opportunities and to provide information to underpin business cases for investment.
Technical energy surveys/feasibility studies are essential to identify savings and provide fact based information for the business cases. These make use of experts to review elements in your estate to identify and quantify viable carbon/ energy saving opportunities.
Lighting accounts for around 20 per cent of the estate emissions and often provides significant opportunities for cost effective savings. There have been significant gains in lighting efficiency particularly though LED. 3 W/m2/100 lumens is a reasonable design target and 60 luminaire Lumens/circuit Watt this is half the figure that would have been used 10 years ago.
In my experience there are opportunities for improvement in lighting systems even in many new hospitals.
Combined Heat and Power (CHP)
Potentially CHP can deliver significant CO2 savings. BRE reviewed the performance of CHP in the NHS, for the SDU, our findings were:
Some CHP plant was running at < 65 per cent efficiency which delivered no CO2 benefits.
Most CHP plant were running at around 72 per cent efficiency delivered CO2 savings of around four per cent. The best six per cent of all CHPs in the NHS were achieving sessional efficiencies of 78 per cent delivering CO2 saving of around eight per cent.
This illustrates the need for CHP plant to be correctly sized and well maintained to maximise carbon savings. As a revenue earning device CHP plant must also run for long hours typically more than 4500hrs/a to be cost effective.
I estimate that the NHS has around five million m2 of roof area suitable for Photovoltaics (PVs). This potentially could generate around 630,000 MWh/a offsetting over 0.3MTCO2 and around £70m worth of grid based electricity with a cost benefit of £108m/a with current Feed in Tariffs(FiT).
The price of PVs has fallen rapidly in recent years – current prices are around one sixth compared with 2008. So, despite that fact that the FiT for new systems is decreasing, the return on investment is around 10-15 per cent, even for small systems. For systems of up to 5mW it is still possible to claim FiT. The FiT is a set rate that is linked to inflation and guaranteed by the government for 20 years. The rate applicable to each system will depend on its size and the energy efficiency rating of the property it is connected to.
The UK’s Solar Trade Association has calculated that solar power electricity will be cheaper than that bought from the grid by 2018-2020, when measured over the system lifetime; typically 30 years. With low cost finance available, this means that the perceptions of capital cost barriers are simply no longer valid. This represents a huge sea change in the way solar should be viewed.
Now is the time to invest as the government is now encouraging the installation of PVon large roofs, so this could be good news for the NHS.
There is also currently a review of planning policy too, which means there may no longer be a requirement to apply for planning permission for any rooftop schemes up to 1MW (6,800m2 of slopped roof).
PV code of practice
Over the last two years BRE has worked with the Institute of Engineering and Technology to develop a new Code of Practice for Grid Connected Solar PV Systems above 50kW to provide system owners and operators assurances of safety and performance of systems at design stage and at the point of commissioning. With both construction and solar industries the BRE National Solar Centre is also in the process ofxsetting up a certification scheme to introduce third party validation to improve the quality of PV installed in the UK.
The next important thing on the horizon for solar power is the integration of PV products into building structures, thus providing architects with the possibility of new aesthetically pleasing designs and materials with which to create attractive buildings. It is expected that in the future this approach will be the norm, rather than the exception.
As well as providing a national focus for PV the BRE National Solar Centre (http://www.bre.co.uk/nsc) provides training and technical consultancy to assist clients looking to get involved with solar, from initial site scoping, through full feasibility studies, up to system specification, technical due diligence and performance monitoring.
Steve Pester, of the BRE National Solar Centre, will be presenting on PVs at the Health Estates conference in October.
How do manufacturers and installers of volumetric offsite construction ensure sustainability and compliance when the key priority is time?