It is not hard to see why. Spiralling energy costs have woken people up to the fact that, for many years, we have been the beneficiaries of cheap energy. In many ways, this provided a too comfortable cushion from the underlying reality – that the world economy was built on an energy source that would one day run out.
Today, of course, the age of cheap energy is over and the reality of diminishing oil and gas reserves all too obvious.
A second factor accelerating the development of new energy sources for buildings is the issue of energy security. Dependence on energy supplies over which you have no control is seen as an unacceptable risk in today’s uncertain world. If someone overseas is controlling your gas supply, it is hard to feel that your destiny is in your own hands.
Those in eastern Europe whose homes and businesses froze as the flow of gas from Russia was turned off - two winters in a row - need no reminding of the vulnerability of energy dependence.
The third driver is the rise of concern over the environment in general, and climate change in particular. This has crystallised in the issue of carbon emissions. The UK government, like many others around the world, has set ambitious targets for reducing carbon emissions, with a particular focus on buildings.
This will require big changes in the way we approach the design and construction of buildings in the future, and the technology we use to heat and cool them.
In the UK it was the Merton Rule that first spurred the drive towards renewable energy for buildings. This required that 10 per cent of a building’s energy must come from onsite renewable sources. Introduced by the London Borough of Merton in 2003, the approach has had a great impact and has since been adopted by the Mayor of London and many councils around the country. In its latest incarnation, it is now part of national planning guidance.
Moving forward, the new framework for the future is set by the government’s goal to cut carbon emissions by 80 per cent by 2050. This is acknowledged to be an extremely ambitious target. It will have significant implications for all of us – whether in the cars we drive or the systems we design and install in buildings.
On the path to this there is a target to reduce carbon emissions by four million tonnes by 2020 – equivalent to taking a million cars off the road. As part of this, the government has also set a target for all new dwellings to be zero carbon by 2016, with proposals to introduce a similar target for commercial buildings by 2019.
It is also making it possible for small-scale producers of energy, such as homes and businesses with turbines or solar panels, to sell electricity back to the grid at a guaranteed price. This will stimulate development local, small scale generation projects.
The next step in putting these targets into effect is the introduction of Carbon Reduction Commitments (CRC). It will be compulsory for relevant businesses and public bodies to enter into these agreements. The scheme will begin next year, and use a carrot and stick approach to encourage building occupants to reduce their carbon emissions.
With the growth in the use of air conditioning, and not least its development to encompass heating, it is seen as a key technology for attention in the drive to reduce carbon emissions and increase use of renewables.
It is worth reminding ourselves that over the past few years the energy efficiency of air conditioning generally has improved dramatically. As a result of intelligent control, better design, and improved technology, modern systems are streets ahead of the leviathans of the past.
The next stage is to draw together the latest technology innovations with a diversity of energy sources to deliver the best solution, in terms of efficiency, carbon emissions and comfort for building occupants.
One of the main options to improve air conditioning efficiency is to harness so-called free-cooling. This involves harnessing cool outside ambient air for use in a building, rather than using energy to drive a mechanical cooling system to produce “artificially created” cold air.
The approach is based on the fact that average temperatures in the UK are around 12 deg C. This means that for a significant part of the time, it is possible to use this as free-cooling to moderate the temperature in buildings.
A further significant saving can be made by recouping energy that would otherwise be lost from a building’s exhaust air through the use of heat recovery. This uses some form of air-to-air heat exchange system to transfer energy from air leaving the building, to warm or ameliorate the temperature of incoming air.
The use of free-cooling coupled with effective heat recovery can reduce carbon emissions from air conditioning by as much as 50 per cent. That is a quite staggering saving.
Heat pumps are another technology with a major contribution to make to carbon reduction. They have been around in the air conditioning industry for many years, as so-called reverse cycle vapour compression cooling systems, but in the era of energy savings they are a technology whose time has come.
Heat pumps harness renewable energy as they collect and upgrade natural low level heat in the environment into a form that is useful for heating or cooling buildings. This ability to soak up naturally occurring energy, like a sponge, and concentrate it puts the heat pump in a different league to traditional technology. It enables a system to get more energy out that is put in, at least in the form of direct electrical energy.
For example, with a traditional heating or cooling system, one unit of energy input will give less than one unit of heating or cooling output. However, with a heat pump, one unit in can result in three, four or even five times that output for useful heating or cooling.
Harnessing the energy contained in the ground, with a so-called ground-source heat pump, is the most efficient approach. This uses a heat exchanger to tap the natural heat and cool of the earth a meter or so beneath the surface.
The temperature of the ground at this level remains more or less constant at around 10 deg C throughout the year. In winter months, when ambient air temperatures are hovering around zero, this offers a significant source of useable energy. Conversely, in summer months, when ambient temperatures rise to 20deg C and above, access to a ground heat sink at 10dec C is a valuable source of cooling.
The downside with ground-source systems is high capital cost, due to the ground works needed to bury the heat exchange pipework. Water-to-air systems extract energy from bodies of water such as lakes or aquifers, and concentrate it for use in buildings. Air-to-air systems extract energy from ambient or extract air for use in buildings. Both of these offer significant savings on energy and emissions for at much lower capital cost.
The principle of moving energy from where it is not wanted to where it is needed is used to great effect in modern heat pump VRF systems. These not only harness available energy from outside air, but – with their ability to simultaneously heat and cool – are able to move energy from warm areas of a building needing cooling, to cool areas of the building needing warming. In this way, impressive efficiencies can be achieved.
There is renewed interest in harnessing solar energy for cooling. The principle is highly attractive in theory, since the sun provides a potential source of energy in direct proportion to the cooling required: when the sun shines hottest and the temperature soars, there is greatest solar energy available for powering cooling.
In the past, a major constraint on the use of photovoltaic (pv) cells to provide electricity to drive a vapour compression cooling system has been the cost and relative inefficiency of pv panels.
Today, however, improvements in silicone technology have produced much more efficient panels that offer a more realistic contribution to the energy input for air conditioning. SANYO has developed a new type of panel rated by Which? as the most efficient in the market.
It is not yet commercially viable to power air conditioning solely through pv panels. However, as the emphasis on renewables increases and technology advances, photovoltaics will undoubtedly have a growing role to play as part of a diversity of energy sources harnessed for use in air conditioning.
In the future, I firmly believe buildings will increasingly depend on a mix of energy sources – embracing both renewables and traditional energy sources. The key is to ensure that the diversified system is under intelligent control, so that at any one time the optimum efficiency and occupant comfort is achieved.
It is this high level integration and control, coupled with the latest developments in energy-harnessing technology, that unlocks the potential of renewables – and turns them from mere “hippy dream” to practical commercial reality.