For most people, sustainability takes on different meanings depending on the context. A practical and actionable definition of sustainable lighting is meeting user needs with the least consumption of energy and other resources. User needs include adequate task and ambient illumination, visual comfort, and an interesting environment. How well lighting minimizes the consumption of energy and other resources can be evaluated by certification through LEED – Leadership in Energy and Environmental Design
Alternative home energy options give us a way of being part of the movement into alternative ideas for energy. The house we live in and the way we power it can be part of the solution. So much is changing at the moment. Building codes, insulation and lighting types, entertainment equipment and cooking methods are evolving. Alternative types of home energy covers many aspects.
Even remembering Thomas Edison’s incandescent light bulb invention illustrates some of the changes already on us. With the amount of power required to generate light – only 10% of the power consumption creates light. The rest is used in heat – which creates a sometimes unwanted side-effect.
LED light production is rapidly advancing and is at a point where it can be useful for alternative energy homes. And although much information currently out there states that there is still some distance to go to create useful lights to replace others available now, in fact very good LEDs are coming on now.
LEED Parameters for Lighting to achieve maximum points:
Light pollution reduction
The lighting design must avoid light trespass from exterior luminaires onto neighboring property, as well as prevent sky glow from both interior and exterior luminaires.
To satisfy the pre-requisite, the overall building design must demonstrate a 10% improvement in building energy performance compared to a baseline performance simulation according and must also comply with mandatory provisions – notably lighting controls.
Controllability of systems
The lighting design must provide individual control so that 90% of the building occupants can adjust lighting to suit individual task needs and preferences. Additionally, all shared, multi-occupant spaces must have lighting system controls.
Daylight and views
To earn 1 point, the design must provide daylight to 75% of the regularly occupied space. The requirement may be met using one of four different methods (all of which require glare control devices to avoid high-contrast situations that could impede visual tasks): simulation, prescriptive analysis, post-construction measurement, or a combination.
To earn a second point, the design must provide direct line of sight to the outdoor environment via vision glazing between 0.8 and 2.3 meters above the finished floor for building occupants in 90% of all regularly occupied areas.
High Performance Light Sources and Luminaires
In terms of building performance, a light source with high efficacy – including the fluorescent ballast or LED driver – contributes directly to energy efficiency and economical operation. Sources with long life further support sustainability through reduced material consumption and cost effectiveness through reduced maintenance. In terms of occupant performance, good color rendering is especially important in workspaces that support face-to-face interaction.
Energy codes require a minimum level of control, but a more aggressive controls strategy enhances both building and occupant performance. Automatic occupancy sensing and photo sensor control provide additional energy savings, while individual controls permit lighting to adjust for different task needs and individual preferences.
Occupancy controls turn lighting off when sensors no longer detect the presence of occupants. Depending on the design of the control, it can turn lighting on automatically when occupancy is detected. This is an auto on/auto off device. Auto on/auto off devices can be incorporated in, or linked to, a photo sensor so that lighting is only switched on automatically when there is insufficient daylight to meet the specified luminance. This is a daylight switching device. Alternatively, the control can be linked to a manual switch so lighting is on only when an occupant turns it on. This is a manual on/auto off device and saves more energy than auto on devices.