Putting it into practice

There are several main areas that need to be addressed in order to achieve a sustainable building:

• an awareness and understanding of design practices that can be incorporated to increase the sustainability of the buildings;
• an awareness of how the members of the project team can bring about the success or failure of successfully implementing sustainability in construction, including the contractor, who can bring practical experience to bear - get the right team on the project;
• educating clients to ensure they are aware of the issues involved, the benefits, and available options - to facilitate informed decisions by clients;
• if sustainability is to be incorporated, setting a clear brief for the design team and contractor's team from the outset so that the agreed goals can be achieved; and
• occupancy - an area easily forgotten, but to get the best out of a building, whether newly developed or just an old building occupied as part of a business or home, the way it is managed can have a big impact on the sustainability of that building outweighing the embodied energy and impact of its construction.
  

These are all areas that a chartered surveyor should be increasingly capable of taking on.

The following is not intended to be an exhaustive list of options available for construction projects on new and existing buildings, however, it gives some examples currently being used that have had a positive impact on increasing the sustainability of buildings.

Photovoltaic cells:

• consist of layers of silicone that act as semiconductors to generate power from the sun - they rely more on general daylight levels and less so on direct sunlight;
• 20m2 generates 1500 kWh/year;
• are produced as tiles for fixing to residential roofs or as add-on systems, with the latter tending to be cheaper, especially for most systems that will simply be bolted on to an existing roof;
  
• a 1kWp system on a typical small house would provide the basic power for the boiler, fridge, heat pump etc; a 3kWp system would provide 92% of the power required and a 4kWp one would provide all of the annual electricity needs (on average, as power will be exported to the grid on sunny days but imported on cloudier winter days);
• cost savings can be considerable - around 1 tonne of CO2 a year;
• little maintenance is required, panels will need to be cleaned and trees kept back from overshadowing the panels.

This diagram shows how pvs work and this report includes a number of photographs showing pvs on buildings.

Solar thermal energy:

• uses the direct radiant heat of the sun to heat coolant flowing through the solar thermal panel;
• is an efficient way of providing hot water, and provides some energy in the winter as well as summer;
• can provide up to 80% of hot water demand in the summer and 20% in the winter;
• panels generally need to be orientated towards the sun at an angle to the horizontal, so they are typically roof-mounted, either integral to the pitched roof construction or as separate unit on a flat roof (horizontally-mounted panels for flat roofs are now being produced);
• can be used in conjunction with pv cells and air-source heat pumps; and
  
• panels can be built yourself, see Biggin Hill Solar

Combined heat and power units (CHP):

• simultaneous generation of electricity and useful heat, using the waste heat from power generation to provide hot water and heated air;
• provide a miniature form of decentralised power generation;
• have an efficiency level of 70-80% (power station electricity is only 40%);
• the number of schemes in the UK has risen relatively slowly, from 1,363 in 2006 to 1,568 in 2010, but saving 4 million tonnes of CO2 annually;
• the government supports installation of CHP for both larger developments (including as part of district heating) and for individual homes;
• domestic (micro CHP) systems are available that can be fitted in place of traditional boilers, and are fitted by the electricity supplier who will then buy back excess power from the consumer. 

On-site wind power:

• is favoured by local authorities;
  
• is not always favoured by local residents!
  
• is increasingly being used by developers to generate 10% of their power through renewable sources, where this is required by the local planning authority;
  
• installation cost is just 20% of the cost of photovoltaic for the same amount of power;
  
• wind turbines can be mounted onto buildings without giving disturbance from vibration (see the Strata building in Southwark, London for the incorporation of large turbines into a building);
  
• what will be effect of future developments next to an existing wind turbine - will there be a 'right to air' similar to rights to light?
  
• Designers need to be aware of the reduced benefits of wind turbines in built-up areas when compared to relatively open land;
  
• To build your own, see Homemade wind generator

Ground source heat pumps:

• there are two versions - bore holes and subsurface pipes;
• bore holes are a series of holes bored down to up to 100m, pipes are inserted into the holes;
• subsurface pipes are similar in layout to underfloor heating with pipes running along the ground within the subsoil;
• the systems use the constant temperature of the earth, with water or antifreeze circulated around the pipe system;
• this provides heated water in winter and cooled water in the summer;
• payback between of 5-10 years, can be as low as 2½ years;
• lower maintenance costs than 'traditional' air conditioning and heating due to fewer mechanical parts;
• each kilowatt of energy put into the system produces 4-5kW out;
• this site also has useful reference diagrams.

Condensing boilers:

• are mandatory under Building Regulations for residential use for new properties and/or replacement of old boilers;
• contain a second heat exchanger that allows the vapour produced during normal working to condense onto it, releasing energy, which is used to preheat the incoming water;
• are 13% more efficient than traditional boilers.

Energy efficient lighting and controls:

• most new office buildings these days incorporate passive infrared (PIR) movement detectors linked to banks of 4 or 6 recessed fluorescent light fittings, allowing greater control for smaller areas to coincide with groups of desks and also for the lights to be switched off when not in use;
• lighting controls can also incorporate daylight sensors so that when there are good levels of natural daylight, the lights will not come on;
• LED lamp technology is rapidly improving and offers a low power output compared to dichroic spotlights, increasingly being used in refurbishment and new-build schemes;
• LED lamps last up to 50 times longer than incandescent lamps and 20 times as long as fluorescent fittings whilst using less energy than either and giving off significantly less heat, therefore helping to reduce cooling loads;

See Ledtronics site for examples.

Air source heat pumps

Air source heat pumps can be used for both commercial and, more importantly, residential buildings. The air source heat pump acts like air-conditioning in reverse, taking latent energy from the air using a condenser unit and using the energy to heat water for the house's central heating system, and for larger systems hot water too. The system consists of an external condenser-style unit with refrigerant pipes linking the unit to the indoor boiler; from here the system is linked to the heating and hot water systems. The external unit is powered by electricity or can be linked to photovoltaic cells to reduce the energy consumption further.

The pumps are 300% efficient, i.e. for every 1KW of electrical energy used, 4 KW of energy is produced. A typical set-up reduces the CO₂ emissions by 35-40% compared to a natural gas boiler system.

Visit REUK for more details on air source heat pumps and diagrams showing how they work.