Renewable Energy Options for Building
When renovating any part of the building envelope, such as the façade and windows, energy efficiency is a prime concern, but renewable energy technologies may also be options. In general, the economics of renewable energy are less favorable with building envelope renovations than with other types such as roof; heating, ventilation, and air conditioning (HVAC); plumbing; or lighting. As with all renovations, the renewable energy additions should be considered in the planning stage of the design process to maximize any potential benefits and reduce costs.
Renovating the façade of a building, including the cladding (the siding or materials covering the exterior of a building) can present opportunities for incorporating daylighting, passive solar heating, or solar ventilation preheating depending on the building orientation and the extent of the exterior renovation.
If the façade of the building is being redesigned, the design may be able to add additional open space and windows and overhangs to enable daylighting for some parts of the building. If this is a goal, it should be specified in project planning. Building-integrated photovoltaics can be incorporated into design elements in a building façade on the south side of the building or into shade structures.
Replacing siding provides the option to access solar ventilation air preheating if the building orientation and solar access is appropriate. This technology works best on a south-facing exterior wall on a facility in a heating-load dominated climate, and can be used to preheat combustion air for boilers or the HVAC system.
Renovating building windows is a terrific opportunity to incorporate daylighting. Window selection is key to controlling solar gain while maximizing usable natural light. In particular, different window types will be needed within the same building based on the orientation of the window and the climate and available shading.
In addition to proper window selection and size, daylighting will also need to incorporate lighting controls and other design elements such as overhangs and light shelves to limit the direct sun and glare into a space or to transmit natural light further into a space.
Passive solar heating is another opportunity compatible with the design of building openings. Windows and overhangs can be used to increase solar gain in the winter while limiting it during the warmer months. Since either of these will affect most choices, passive solar must be integrated as early as possible into design, preferably in the planning stage as it will affect all aspects of the design.
A last option that can be considered in window design is building integrated photovoltaics incorporated into windows. Although this is rarely a cost-effective use of photovoltaics, it can provide a small amount of power while giving a clear visual signal of the buildings sustainable nature.
The building envelope presents many opportunities to integrate efficiency measures that will increase energy savings and reduce energy use. Such measures include use of high-performance fenestration systems and sun control and shading designs and technologies. The Whole Building Design Guide provides a Building Envelope Design Guide that covers exterior envelope design and construction for institutional and office buildings.