The World Business Council for Sustainable Development (WBCSD) energy efficiency study on buildings indicated, the worldwide building sector needs to cut energy use in buildings by 60% before 2050 in order to meet global climate change targets set by the Intergovernmental Panel on Climate Change (IPCC). WBCSD also stated that buildings consume over 40 percent of the world’s energy with carbon emissions that are substantially more than the transportation sector. WBCSD recommended that governments and businesses aggressively reduce energy use in new and existing buildings to reduce the planet’s carbon footprint by 77 percent or 48 Gigatons.
Integrating wind turbines into commercial and public buildings, from the stakeholders’ perspective, comes primarily from the desire to reduce energy costs to operate the building. However, many projects are undertaken through a sense of social responsibility to reduce greenhouse gas emissions, carbon footprints, retain tenants and gain a market edge in a competitive building market. Energy efficient buildings are a rapidly growing initiative, the result of which will benefit the environment, building owners, tenants and help to meet IPCC targets.
The Oklahoma Medical Research Foundation building represents an excellent example of how a roof top wind farm can be successfully implemented. The installation is projected to cut carbon emissions by approximately 2 million pounds annually. A great deal of research and analysis was conducted before the placement of the turbines on the OMRF structure. The installation is now considered to be the largest roof top wind farm in the US.
The most important phase for creating a successful Building Integrated Wind Turbine (BIWT) project is proper and thorough site assessment. First and foremost is to assess the wind regime in the regional, local and immediate area around the existing building or location of where the new building will be built.
It is important to understand local air flows around and over buildings through a combination of computational fluid dynamics modeling and measurements, which are conducted with anemometers and wind roses. The wind rose is a graphic tool used by meteorologists to give a succinct view of how wind speed and direction are typically distributed at a particular location. Historically, wind roses were predecessors of the compass rose (found on maps). Using a polar coordinate system of gridding, the frequency of winds over a long time period is plotted by wind direction, with color bands showing wind ranges. The directions of the rose with the longest spoke show the wind direction with the greatest frequency.
Assessing the noise and structural implications of BIWT’s for a building structure is the next requirement. We do this by determining all possible attachment methods and assessing appropriate load-bearing capacities as well as safety standards specified by local building regulations. A full range of turbulence and wind shear calculations are required as well.
When designing the building it is important to optimize the structure to increase wind capture and flow velocities through the wind turbines. Wind rose data will guide the architect in the geographical placement of the building or the placement of the BIWT’s. The architect can creatively design into the building a means to channel wind energy and focus it into the wind turbines. In effect, using the roof top building envelope itself, one can dramatically increase the swept area for wind capture and can easily double the power performance of a BIWT.