It is rarely possible to do everything we would like to reduce the environmental impact of building projects. It takes time to research alternative design and construction systems; new materials may not have proven track records; higher costs may be an impediment; or clients simply might not be interested. Therefore, it makes sense to figure out where our efforts will do the most good. Where should we focus most of our attention in designing and building structures that will have minimum impact on the environment?
Some designers and builders who emphasize sustainability have picked out just one aspect of green design—often it’s recycled-content building materials—and hold that up as their flag. Material selection is one of the most visible green building strategies and often the easiest to point to—but it is usually not the most important. Deciding which measures are most important is no simple task. Here we take a look at some of the factors to consider and suggest a listing of priorities in green design. This sort of list can never be considered final—we look forward to an ongoing discussion of priorities that we might all learn from.
Several related factors should be considered in making objective decisions about where our investments of time and money will do the most good in reducing environmental impact.
First, we need an understanding of what the most significant environmental risks are. These may be global in nature, or more specific to your particular region or site. Prioritizing these risks is difficult because often they occur in unrelated fields, with no way to make direct comparisons. Which is worse, the release of toxic waste, destruction of an endangered species’ habitat, or stratospheric ozone depletion? Interestingly, scientists often come up with very different priority rankings than the general public on these issues (see sidebar).
The second critical factor is an understanding of how our buildings contribute to these risks, and how significantly the measures we adopt can help the situation. We may decide, for example, that ozone depletion, a global problem, is more important than the survival of a particular bird species. But if a building project we’re working on could eliminate the last remaining habitat of that species—a major contribution to its demise—that’s probably a higher priority than reducing our use of HCFCs, which are contributing incrementally to ozone layer damage. The third factor has to do with the specific opportunities presented by each individual project. On some projects one can dramatically affect a building’s performance in one particular area with very little investment, while addressing other impacts might prove very expensive and only minimally effective. Energy performance, for example, can sometimes be improved by simply adjusting a building’s orientation, while using a recycled-content floor tile might increase cost significantly for relatively little gain.
Finally, we have to consider the available resources and agenda of the client. There are often measures that can be taken at no additional cost—some may even save money—to reduce environmental impacts. Implementing such measures should be a “no-brainer.” Other measures might increase the first cost of a building, but save money over time. How far we can go with such measures, in length of payback and size of initial investment, depends a great deal on the resources and willingness of the client. In some cases a third party can be found to finance such measures, and share in their savings. There are also measures that are important environmentally but don’t offer the building owner any direct financial reward. Pursuing these strategies depends on the client’s good will, environmental commitment, and interest in some of the less tangible benefits that may result, such as good public relations. Given all these factors to consider, deciding which environmental goals to pursue on a given project might seem overwhelming. To provide a more concrete starting point, we’ve come up with a list—EBN’s priority ranking of measures to reduce the environmental impact of buildings. Clearly the order is arguable, and for specific projects and climatic regions a different order will apply. All the measures listed below are important, and one should definitely implement any that are feasible within the constraints of a particular project.
This list—a builder’s dozen—reflects our sense of where you might look to get the most bang for your buck.
The ongoing energy use of a building is probably the single greatest environmental impact of a building, so designing buildings for low energy use should be our number one priority. Decisions made during the design and construction of a building will go on affecting the environmental performance of that building for decades to come—perhaps even centuries—through energy consumption. An integrated design approach can often take advantage of energy savings that become feasible when the interaction between separate building elements, such as windows, lighting, and mechanical systems, are considered.
•In buildings with skin-dominated energy loads, incorporate high levels of insulation and high-performance windows, and make buildings as airtight as possible. •Minimize cooling loads through careful building design, glazing selection, lighting design, and landscaping. •Utilize renewable energy resources to meet energy demand. •Install energy-efficient mechanical equipment, lighting, and appliances.
Cost implications: Likely to increase first cost, but significant savings in operating cost can often be achieved. Reduced heating and cooling loads may also reduce first cost of HVAC equipment, helping justify the expense.
Existing buildings often contain a wealth of material and cultural resources, and contribute to a sense of place. In some cases the workmanship and quality of materials that has gone into them is almost impossible to replicate today, making the restoration all the more valuable.
•Do not ignore priority #1, above. When restoring or renovating buildings, maximize energy efficiency. •Handle any hazardous materials appropriately (lead paint, asbestos, etc.).
Cost implications: Usually—but not always—less expensive than building new. These projects can be difficult to budget.
To reduce environmental impacts, we must address transportation. Even the most energy-efficient, state-of-the-art passive solar house will carry a big environmental burden if its occupants have to get in a car each morning and commute 20 miles to work. Since the 1940s, zoning and land-use planning have, in general, been impediments to, rather than supporters of, responsible transportation patterns. Effective land-use planning can also help to foster strong communities.
•Design communities that provide access to public transit, pedestrian corridors, and bicycle paths. •Work to change zoning to permit mixed-use development so homeowners can walk to the store or to work. •Incorporate home offices into houses to permit “telecommuting.” •Site buildings to enhance the public space around them and maximize pedestrian access.
Cost implications: Smaller and shorter roads, services lines and storm sewers should reduce costs. Obtaining zoning variances can be time-consuming.
Smaller is better relative to the environment, and no matter what the materials, using less is almost always preferable—as long as the durability or structural integrity of a building is not compromised. Reducing the surface area of a building will reduce energy consumption. Reducing waste both helps the environment and reduces cost.
•Reduce the overall building footprint and use the space more efficiently. •Simplify the building geometry to save energy and materials. •Design building dimensions to optimize material use and reduce cut-off waste. For example, design buildings on a 2’ or 4’ (600 mm or 1,200 mm) module. With light-frame construction, use 24”-on-center framing and headers sized to each opening.
Cost implications: Some additional design time may be needed, but overall, this strategy should save money, particularly with larger projects and multiple-building developments. Increasingly, we need to consider not only the cost of buying materials, but also the cost of disposing of what’s left over—by reducing waste we save both ways. A 4x10 (1,200 mm by 3,000 mm) sheet of 5⁄8” (15 mm) drywall, for example, which costs about $8 to buy, now costs more than $4 to landfill in some areas!
In fragile ecosystems or ecologically significant environments, such as old-growth forests or remnant stands of native prairie, this might be the highest priority.
•Protect wetlands and other ecologically important areas on a parcel of land to be developed—on some sites you should reevaluate whether development should be carried out. •On land that has been ecologically damaged, work to reintroduce native species. •Protect trees and topsoil during construction. •Avoid pesticide use—provide construction detailing that minimizes the need for pesticide treatments. •With on-site wastewater systems, provide responsible treatment to minimize groundwater pollution—there are several innovative new wastewater treatment systems that do a better job at nutrient removal than conventional septic systems.
Cost implications: Some of these measures cost less than standard practice, others cost more. Maintenance costs with natural landscaping are often much less than for conventional practice.
Most—but not all—of the environmental impacts associated with building materials have already occurred by the time the materials are installed. Raw materials have been extracted from the ground or harvested from forests; pollutants have been emitted during manufacture; and energy has been invested throughout production. Some materials, such as those containing ozone-depleting HCFCs and VOCs, continue emitting pollutants during use. And some materials have significant environmental impacts associated with disposal.
•Avoid materials that generate a lot of pollution (VOCs, HCFCs, etc.) during manufacture or use. •Specify materials with low embodied energy (the energy used in resource extraction, manufacturing, and shipping). •Specify materials produced from waste or recycled materials. •Specify materials salvaged from other uses. •Avoid materials that unduly deplete limited natural resources, such as old-growth timber. •Avoid materials made from toxic or hazardous constituents (benzene, arsenic, etc.).
Cost implications: Some resource-efficient products are available at no extra charge; others may cost more. Installation may differ from standard practice, raising labor cost if installer is unfamiliar with a product.
The longer a building lasts, the longer the period of time over which the environmental impacts from building it can be amortized. Designing and building a structure that will last a long time necessitates addressing how that building can be modified to satisfy changing needs.
•Specify durable materials—this is usually even more important than selecting low-embodied-energy materials. •Assemble the materials to prevent premature decay. •Design for easy maintenance and replacement of less durable components. •Design for adaptability—particularly with commercial buildings. •Allocate an appropriate percentage of building funds for ongoing maintenance and improvements. •Consider aesthetics during design, and whether a particular style is likely to remain popular—the idea of “timeless architecture.”
Cost implications: Though not necessarily more expensive in all cases, building for durability usually does require a larger initial investment. Preventative maintenance also requires ongoing investment, though it is generally cheaper over the long term than repairs due to insufficient maintenance.
This is largely a regional issue. In some parts of the country, reducing water use is much higher on the priority list.
•Install water-efficient plumbing fixtures and appliances. •Collect and use rainwater. •Provide low-water-use landscaping (xeriscaping). •Separate and use graywater for landscape irrigation where codes permit. •Provide for groundwater recharge through effective stormwater infiltration designs.
Cost implications: Most of these measures will add to the cost of a project. Some savings in lower water and sewage bills and longevity of on-site septic systems can offset the additional costs. Designs that promote stormwater infiltration are usually less expensive than storm sewers.
Though some people tend to separate the indoor environment from the outdoor environment, the two are integrally related, and the health of the building occupants should be ensured in any “sustainable” building. With many clients, this is the issue that first generates interest in broader concerns of environmentally sustainable building.
•Design air distribution systems for easy cleaning and maintenance. •Avoid mechanical equipment that could introduce combustion gases into the building. •Avoid materials with high rates of VOC offgassing such as standard particleboard, some carpets and adhesives, and certain paints. •Control moisture to minimize mold and mildew. •Introduce daylight to as many spaces as possible. •Provide for continuous ventilation in all occupied buildings—in cold climates, heat-recovery ventilation will reduce the energy penalty of ventilation. •Give occupants some control of their environment with features like operable windows, task lighting, and temperature controls.
Cost implications: Most of these measures will increase construction costs, but they often are easily justified based on the increased health, well-being, and productivity of building occupants. Failure to pursue these measures can lead to expensive “sick-building” lawsuits.
For more and more materials, sorting and recycling job-site waste is paying off economically, and it can certainly generate a good public image.
•Sort construction and demolition waste for recycling. •Donate reusable materials to nonprofit or other community groups where they can be used to build or improve housing stock.
Cost implications: Additional labor to sort and recycle waste is often offset by the savings in disposal costs, though these vary by region. Sorted material can sometimes be sold for a profit.
In addition to creating buildings with low environmental impact, you should practice environmentalism in your own business, thus serving as a model for other design or construction firms.
•Purchase fuel-efficient company vehicles and promote use of public transportation and carpooling by employees. •Use recycled paper in your office and recycle wastes generated in your office. •Use the design process to educate clients, colleague, subcontractors, and the general public about the environmental impacts of buildings and how they can be mitigated.
Cost implications: Carpooling and public transportation can save money for employees, while reducing the number of parking spaces the business must provide. Recycled paper, for most applications, is only slightly more expensive than virgin.
In deciding which measures to pursue on specific projects, consider the relative benefits of the different measures. You might begin by customizing the list for your region. In an arid climate, for example, water conservation would go near the top, while in a city prone to smog inversions, transportation alternatives might be the most important. Then refer to your list as you consider each project, and identify the areas where you can do the most for the environment. Pick the low-hanging fruit first, and go after the tougher issues as time and resources allow. Return to buildings you’ve completed to see which systems are working and which aren’t, and how occupants have modified your work to fit their needs. When possible, use your buildings to strengthen the link between occupants and the global environment through education and direct interaction. Finally, if you are incorporating environmental features into your work, take advantage of that fact in your marketing efforts. We hope that this ranking will serve to inspire others who regularly think about environmental impacts of building to offer their opinions. Like most lists and categories, this list serves a purpose but also carries the risk of compartmentalizing the design and construction process. Often the most significant opportunities for benefiting the environment come from a careful integration of the design, taking advantage of synergies between building elements. The most elegant design solutions—those that reduce complexity while solving multiple problems—won’t be found by considering each item on this list in isolation. In the next few issues of EBN we hope to include letters from readers on this important question: Where should we focus our greatest effort in reducing the environmental impact of our buildings? Let us know your thoughts.