The world of building services is changing out of all recognition. But the technologies which must be used in the future are, surprisingly, more familiar than you think. Jim O'Neil, chairman of M&E Sustainability, discusses the issues
THIS year promises to be a major year for renewable building services systems, says M&E Sustainability chairman Jim O'Neil
The year began with the news that more than £25M worth of grants have now been claimed for small-scale renewable schemes from the government's Low Carbon Buildings Programme (LCBP). This includes £7.5M for 4,600 household installations and £18M for 739 school, community, housing association and commercial building installations.
At the turn of the year, there was still £11M worth of grants available under Phase 1 for householders wishing to install renewables and £44M for schools, charitable bodies and other public sector organisations under Phase 2 of the programme.
The grant system became embroiled in controversy last year because of the difficulty many people had in gaining access to the funds, but improvements have been made to the bureaucracy. In any case, it is due to end later this year so there is a real incentive for people to grab the cash while it is there and before government takes it away.
Last year also ended on a positive planning note with the government's new Planning Policy Statement explicitly stating that all local councils must support on-site renewable and community energy schemes. Planning officers must also consider the potential for connecting developments to neighbouring community heating and power schemes that can serve an entire local community.
The Communities and Local Government department stated: 'These plans build on the Merton rule, which requires all new non-residential developments above a certain size to generate at least 10% of their energy on-site from renewable sources, or the Mayor of London's plans to double renewables' share of UK electricity supply to 20% by 2020.'
Planning officials will have to learn to be more intelligent about issues like south-facing sites, which have greater solar capture potential, and the use of windy areas close to developments and aquifers for ground source heating. Siting housing developments close to business and industrial centres, which can provide surplus heat from offices and factories for domestic use, also makes sense.
'It's all about local power,' said housing minister Yvette Cooper. 'If we are to reach ambitious zero-carbon standards, we need a revolution in the way we heat and power our homes. We want councils to do more to back local green energy.
'We need to be environmentally ambitious about all buildings, not just housing,' she added. 'We don't just need eco homes - we need eco offices, eco shops, eco pubs and clubs. And surprisingly the technologies to do it may be considerably more familiar than many people think.'
Indeed many of the technologies are increasingly well proven. And the building services sector is becoming better trained and equipped to get the best from these solutions.
According to research body BSRIA, the UK market for solar thermal technologies will increase by 40% between 2006 and 2010. Heat pumps are also predicted to grow by a staggering 57% in the same period; with photovoltaics (PV) rising by 26% and biomass boilers by 20%.
Solar water heating is benefitting from the improved insulation levels of British buildings, which have reduced the amount of energy required to heat occupied space.
As a result, hot water production accounts for a higher proportion of our energy consumption and solar panels are ideal for reducing the carbon footprint of this process.
Once solar heating is installed, it is almost entirely maintenance free. And a 4m2 array will provide up to half of an average family's hot-water needs for the year. Normally used to supplement a conventional water-heating system, solar panels will cut the amount of heating fuel used by between 40% and 60% - which is equivalent to 1,500kWh per year, according to the Solar Trade Association.
The cost of installing a solar hot-water system ranges between £2,500 and £4,000 dependent on the size of the system and whether flat-plate or evacuated-tube collectors are used. But many end users are taking advantage of the LCBP grants to offset part of this cost.
A typical domestic installation in the UK would have a panel area between 3m2 and 4m2 when using flat panels and about 2m2 with evacuated tubes. The storage cylinder will typically have capacity for 200-300 litres depending on usage patterns in the building.
The solar installation must be carefully integrated with any existing heating system to provide the benefits to the end user - only fully trained and experienced heating engineers should be employed to carry this out.
The position of the installation is important both from an aesthetic and performance point of view and contractors need to discuss this in depth with the customer.
Heat pumps make full use of solar energy absorbed by the earth, water and air. They extract that heat and use it to pre-heat water for space and water heating so reducing the amount of gas, oil or electricity consumed. Depending on the type of heat pump, they are three to six times more efficient than conventionally fired boilers.
A heat pump works like a fridge in reverse. While a fridge takes heat out of the food stored inside and releases it into the room, the heat pump extracts heat from surroundings. It then brings this heat up to a temperature sufficient for central heating (55-60˚C).
This works in the summer as well as in the winter 24 hours a day. As it is a low-temperature heat source - unlike conventional central heating, which operates at high temperatures - larger heating surfaces such as underfloor heating and low-surface-temperature radiators are the best way to extract maximum efficiency.
Depending on the plot size and ground conditions, slinky loops can be buried a metre or two below the surface in horizontal trenches or pipes in vertical boreholes drilled down to around 100 metres.
The higher the temperature of the heat source, the more efficiently the heat pump will operate, but the key thing is having a constant temperature. The earth around UK buildings is on average a constant 12˚C, which is ideal.
The heat is collected by polyethylene pipes filled with a water and anti-freeze mixture that extract about 50 Watts of heating energy per metre in a borehole or 25 Watts per square metre with the horizontal coils.
Air source heat pumps are not as efficient, but probably have greater market potential as they are easier and cheaper to apply because they do not require any groundworks. They extract heat from the air and can be installed either inside or outside the building.
Open-loop water source heat pumps can be the most efficient of all as they use heat extracted directly from a body of ground or surface water. In this case, the water from the source is pumped through the system. This source water is also effective for air conditioning, particularly chilled beams and ceilings.
Issues that contractors must take into account is potential disruption caused by groundworks for the ground source systems, the fact that air source systems are less efficient and can be unsightly and for water source heat pumps a handily placed large body of water is required.
Photovoltaic (PV) modules are growing in popularity as another way of exploiting solar energy - this time to produce electricity. It is estimated that were we able to capture all of the potential power provided by solar radiation to the earth we could deliver 15,000 times the whole world's power needs. Around 1,000 Watts falls on each square metre of the earth's surface in a Northern latitude country like the UK, although on a dull day this will drop to only 20 Watts.
PV modules are a network of solar cells built from silicon or similar semi-conductor materials that generate electricity when exposed to light. This power is then transferred into a row of batteries for storage and later use.
The modules must face south and be at an angle of 30˚ for optimum performance.
In a number of European countries, but not the UK so far, PV systems are tied to the national grid and owners receive a guaranteed price for the power they produce. However, the UK national grid is not geared up to receiving electricity back from microgenerators so currently PV is only used to provide on-site power.
PV is also extremely expensive at the moment because of the global shortage of silicon and extreme competition for this resource. This means the payback period is extremely long making PV rarely a sensible investment.
Biomass, on the other hand, is often referred to as the virtuous
circle because the plants grown to produce heating fuel absorb the CO2 emitted when their predecessors are burned. The wood pellets can also be sourced from waste wood that would otherwise be discarded at the end of timber processing. The pellets are formed from natural, untreated wood collected from wood shavings, sawdust or forestry offcuts - two kilograms can produce about the same amount of heat as a litre of heating oil. Pellets are burned in stoves,
central-heating boilers and large district heating schemes. They are delivered by tanker and kept in
a silo or underground storage bunker. The system for delivering the pellets to the boiler requires fairly sophisticated engineering and high safety standards.
Existing oil-fired heating systems can be converted to work with bio-fuel, which has major potential as the transport industry, and is also driving development of this fuel from rapeseed, sunflower and palm. In Germany more than six million oil systems are being converted. Modern burners are able to cope with the new generation of biofuels and the existing storage and transportation systems can be retrofitted to accommodate this new approach.
Contractors do need to weigh up whether it makes sense to opt for biomass or biofuel if the fuel needs to be transported large distances so increasing vehicle carbon emissions and undoing much of the good work.
Also, does the property in question have adequate space for the substantial storage facilities required? And is the end user aware that they are subject to intensive fire safety measures with biomass, for example?
Wind power will continue to have some impact on the market. Micro turbines enjoyed a surge of interest when various DIY retailers starting promoting them. But actual performance was disappointing often because of inappropriate siting of the devices and unrealistic claims. Planning permission is likely to still be required even with the newly liberalised planning laws because turbines do have an impact on lines of sight.
Fuel cells too will have an impact in the future. But that technology for building services applications remains in its infancy.
The main activity for our sector will be heat pumps, solar collectors and biomass in the coming months and years. Many specialist contractors have already geared up for
this potentially lucrative business area by undertaking appropriate training.
Building services companies have the necessary core skills and the HVCA is actively involved in the development of professional standards and business support through its joint M&E Sustainability initiative with the Electrical Contractors Association.
For more information about renewable technologies and training go to www.mech-elec.org.uk.