In planning for the construction of a building with sustainable design features and the reduction of building and building user energy usage, it is important to plan strategically from the very start of a project (and even earlier when possible). It cannot be emphasized enough that early decisions can have the greatest impact on achieving sustainable design goals. From the selection and planning of a site to the conceptual design of the building, the decisions made at these early stages can make the difference between a project that successfully meets a client's sustainability and energy usage goals and one which falls short. The considerations I discuss here are important for those taking the ARE®, particularly the Programming & Analysis exam and the Project Planning & Design exam.
At the earliest stage of pre-design, site selection is an important factor in sustainable design considerations. Unfortunately, this is typically beyond the scope of an architect's services and undertaken by a client prior to the engagement of an architect. If, however, the circumstances of the project allow input from the architect at this early stage, the following factors are among those that you should consider. The first is the possibility of the reuse of existing buildings rather than the construction of entirely new buildings. By far, the reuse of an existing building typically requires significantly less embodied energy than the construction of a new building. There are likely challenges to the building's ability to accommodate some green building features, but in many cases, successful energy retrofits can be carried out. This is, however, assuming that a client will be able to accomplish their programmatic goals within the constraints of an existing building, which may not be the case. In some cases, where adaptive reuse is not possible, the best option may be to construct an addition to an existing building.
3. Consider an Environmental Perspective
Where the reuse of an existing structure is either not possible or not desired by the client, the next consideration is where the project is to be located. The preferred site location, from an environmental perspective, will depend on the type of building project, the number of employees, and other considerations. But the possible location of the project within an urban environment should be considered for the following factors, among others: access to public transportation, walkability for employees (including access to community amenities such as restaurants, shops, and public parks), proximity to bike lanes, and the use of existing public utilities or site features.
4. Try to Affect the Environment as Little as Possible
If an urban location is not feasible and a less densely populated area is the necessary site location, then you should consider a number of other factors for the project to have as little environmental impact as possible. In general, proximity to population dense areas, along with the community amenities mentioned above, is desirable in order to reduce potential employee commuting times or driving times to various amenities. Previously developed lots or sites are preferable so as to not disturb undeveloped land and habitats. Certainly, you should avoid protected areas such as wetlands. Existing trees and shrubs should be retained where possible. Locating a project within already developed areas has the added benefit of ready access to existing utilities. If the project takes on the remediation of a brownfield or previously contaminated site being underutilized-as may happen with a desired location in an urban area-the project is able to succeed not only in having a positive environmental contribution to the land, but also in potentially increasing the value and density of an already developed area.
5. Avoid Unnecessary Paving
For any necessary paved areas, whether access roads, driveways, or parking lots, you should consider using permeable paving. This has the dual benefit of reducing site runoff and reducing addition to the heat island effect, which can be understood as an increase in outdoor air temperature due to the emission of heat from manmade elements such as asphalt and concrete. In any event, avoid unnecessarily paved areas. Green spaces and plantings have multiple benefits for site users, including the provision of shade, access to quality outdoor space, the avoidance of heat island effect, and reduced site runoff. Bioswales and rainwater gardens should be considered for their potential to likewise reduce stormwater runoff and pollutants. The reduction of stormwater runoff is particularly important where municipal systems utilize a combined sewer and stormwater system. Such systems can become overwhelmed during large storm events, with excess flows being directed without treatment into rivers or other bodies of water, affecting the local ecosystems and water quality.
6. Utilize Trees to Help Regulate Building Temperature
The use of trees, whether existing or added as part of a project's scope, can also be strategically utilized to reduce solar irradiation on building facades. If you select deciduous trees, the leaves can block solar gains during the summer (reducing cooling loads of the building's HVAC system) while allowing them during the winter (potentially providing some passive heating and consequent reduction in heating loads). When utilizing pavement or concrete, consider lighter color materials for their ability to reflect rather than absorb (and emit) solar heat.
7. Reflect on Topographical Conditions
Also, consider the topographic conditions of the site. Site design which makes use of existing features without significant modification to grading is desirable, as cutting, filling, and soil hauling operations can have a significant effect on the environment. The prevention of soil erosion and sediment control, both during construction and afterwards, is also desirable. Erosion has the potential to degrade the ecological features of the immediate site as well as disturbing waterways and the habitats they provide.
8. The Effects of Orientation
In tandem with the conceptual building design, carefully consider the orientation and position of a building on a site. Among considerations in this respect are how much daylighting of interior spaces may be achieved as well as opportunities for passive heating and cooling. For example, do surrounding buildings shade particular areas of the building facade? If so, how does this affect the solar heat gains on the building, particularly with respect to window or curtainwall locations on the building facade? Is there a particular direction from which wind blows that can be taken advantage of in order to provide effective cross-ventilation in the building? In analyzing a site, and in addition to the microclimatic and site-specific features discussed above, you should consider more general climatic factors such as temperature, humidity, and precipitation. Depending on the climate and landscaping features desired, there may be opportunities for the collection of rainwater for use in watering landscape plantings on the site, as it is desirable to limit or eliminate the usage of potable water for such purposes. In regions where little water is available, consider using native plantings which do not require additional watering for water conservation.
9. Consider Light Pollution
Lastly, consider the potential for light pollution from a site, as this can have a negative impact on wildlife and disturb human sleep patterns. Also, consider the more general possibility of creating a negative visual impact on any areas where the natural features of the landscape may be recreationally enjoyed.
The above considerations in site selection and planning for sustainable design are by no means exhaustive but are factors that should be considered. Each particular project will have its own challenges and constraints, but also unique opportunities which careful site and programmatic analysis may reveal.