Though a universally accepted definition of a green building is still a work in progress, several experts agree that a green building is designed to use resources more efficiently and provide a high degree of comfort to users. In conversations around green buildings, the triple bottom line approach is often mentioned; a green building must combine environmental conservation with social and economic benefits. This article focuses on some of the environmental aspects of a green building, including;
The consideration of the whole life cycle of the building
Also referred to as the cradle-to-grave analysis, it involves assessing the projected environmental impacts starting from the design, construction, operation and demolition/upgrade. On the contrary, most ‘conventional’ buildings only consider the effects on the environment during construction.
Site impact and ecology
A green building is designed to minimize the disturbance of native wildlife and vegetation. Further, it aims to reduce the effects of construction like pollution on the surrounding. If feasible, the re-use of old sites is encouraged (brownfield development).
After construction, there is the reintegration/restoration of displaced plant and animal species where possible, or else replacing them with similar species that will quickly adapt to the local conditions.
The first approach is the design of the building to maximize the use of natural lighting, heating and cooling to reduce the reliance on mechanical systems to serve these needs. This reduces the energy demands of the building. Where there is the need for electrical appliances to augment the natural systems, priority is placed on energy-efficient gadgets with high-energy ratings. Overall, this reduces the energy consumption of the building.
Having minimized the energy demands and consumption, a green building places emphasis on renewable energy like solar, wind and thermal energy to meet the needs of lighting, cooking, heating, ventilation and air-conditioning (HVAC). This could be through on-site generation or off-site importation.
A green building is designed to use water more efficiently. This is sometimes done through the use of high-efficiency taps and showerheads, and water-efficient toilet flushing systems. This ensures that less water is required for these functions. Beyond that, there is the use of potable water for only potable uses or vice versa. Rainwater harvesting is also in practice. These range from collection off the roof to collecting site run-off into underground storage facilities.
Materials and waste
In seeking to create the least environmental impacts, a green building uses construction waste during its construction where applicable. What’s more, a green building sources most of its building materials from the local region. Where this is not feasible, the materials to be used are sourced within a certain radius of the site of construction. Materials more suited to the local climatic conditions are usually preferred. All this aims at reducing the distance it takes to transport the building materials, and the energy used in transporting these materials. (embodied energy)
There is also an emphasis on a reduction in the waste generated, from construction to operation. Measures to recycle the waste generated are then employed. Some waste is treated on-site first, (think greywater), before being channelled to public sewage facilities for treatment.
In summary, a green building covers so much more than just environmental conservation. Even so, the points listed here are by no means exhaustive. Proximity to public transport facilities, indoor air quality, general comfort of users is other aspects not even mentioned. What other environmental factors have been left out?