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Wind power

5 June 2014  

Discovering ways in which to eke out more energy savings is a high priority for organisations in 2014. 

According to the 2011 Energy Act, commercial buildings with low Energy Performance Certificate (EPC) ratings will be unlettable. The result is that organisations are putting energy saving measures into place now, rather than later.

Geoff Smyth, head of technology and delivery at the Carbon Trust, believes that energy conservation measures should be the first priority. “We take a pragmatic approach to energy management within buildings,” says Smyth. “We look at the building services engineers to design energy-efficient systems.”

Once all possibilities of minimising energy consumption have been exhausted, FMs may turn to on-site renewable energy sources, says Smyth.

Installing photovoltaic (PV) technology to harness solar power is arguably the simplest project from an installation and subsequently an operations perspective. Smyth is of the view that solar power is the most cost-effective for electricity generation, although the efficiency of PV is still developing.

The UK government, which is legally committed to meeting 15 per cent of the UK’s energy demand with renewable sources by 2020, is also increasing the use of onshore and offshore wind. 

Wind power is becoming an increasingly popular energy source and FMs may be looking to follow the country’s footsteps and install a turbine on site.

Gale force
While wind power can flourish, there are stumbling blocks preventing widespread use for single organisations. Logic dictates that wind turbines should thrive when integrated into a tall skyscraper, or mounted on top of a tall building, where it would enjoy faster wind speeds.

The Strata SE1 residential building in Elephant and Castle, London, was fitted with three nine-metre turbines on the top of the building. But those who frequent London may notice that quite often the blades are stationary. Reports suggest that the turbines, installed to provide an estimated 8 per cent of the energy needs of the building, caused vibrations and noise pollution in the apartments on the upper floors. 

Wind data is still being collected and analysed for the site, leaving questions about their true energy potential.

Big is better
Alex Wilson, founder and executive editor of BuildingGreen in the US, is a strong advocate of renewable energy, including wind power. But his examination of the possibilities available presented a disappointing landscape.

He explains that wind turbines “almost never make sense on buildings – even tall buildings”.

“They [turbines] have to be small so that they won’t affect the building’s structure.” 

Wilson says the wind movements at the top of taller buildings can be turbulent. “Wind turbines don’t like turbulence; they do much better with laminar wind flow.”

Smyth believes that there simply isn’t a business case for small-scale wind turbines.“It really is a case of ‘big is beautiful’,” says Smyth. “The bigger the turbines, the more significant the yield and more cost-effective the deployment. For small turbines, you are looking at a payback in excess of 10 years, if you will get a payback at all.”

A report published by the Carbon Trust in 2008, titled Small-Scale Wind Energy: Policy Insights And Practical Guidance, concluded that small turbines in urban locations often achieve a capacity of less than 10 per cent; that is they produce just a tenth of their potential output. This figure, says Smyth, can often be as low as 1 per cent. 

He also estimates that an organisation would spend between £2,500 and £5,000 per kilowatt installed for a small-scale system. So wind power looks a costly option for a small fraction of a building’s energy needs. 

Turbine troubles
Should an organisation wish to install a larger wind turbine, careful research must first be undertaken to determine whether installing turbines is an option.

“You need to look at the height of the turbine and how that relates into the context of its surroundings,” says Smyth. “It is not simply a case of planting these new technologies on a building.”

“Wind speed data should be accumulated and analysed to make sure [they] are going to enjoy appropriate wind speeds. In addition, other structures on the roof, such as water tanks, and neighbouring buildings, could have an impact on the flow of the building.” 

Limits on how long the turbines can be kept on each day could also dent any further savings from using the system. Smyth explains that large turbines that are placed adjacent to buildings – instead of integrated into them – could cause shadow flicker, depending on the location of the sun and the direction in which the building is facing, causing disturbance to the building’s occupants and resulting in the system being switched off. 

Flying the flag

This article originally intended to explore the options available to organisations to develop wind power as a primary renewable source of energy. The options are, however, currently scarce.

The technology must overcome the challenges put forward by Wilson and Smyth. A turbine, or other device, must be able to exploit the turbulent, yet faster, winds found swirling around tall buildings in urban settings. Turbines must be able to generate sufficient electricity to offset the energy and carbon required to manufacture and install them.

Only once the technology is able to produce significant levels of energy in an efficient manner will wind power be able to fly the flag for renewables. 

Jamie Harris is a reporter at FM World