Editor’s note: This article is the third in a series of occasional stories on green building by Carl Seville.
You’ve decided to green-certify your property, and you’ve chosen your program. Now, you need to do the right things, in the right order, to get through the certification process with the least impact on your schedule and budget.
When you use a GPS on a trip, if you make a wrong turn, it adjusts and puts you back on the right path. There is no green building GPS that will self-correct as you go, so you have to make all the right decisions from the very beginning. When you make a wrong decision early in the process, it can cost you money, time, long-term energy costs, and increased maintenance for the life of the building. A similarly lost opportunity occurs if you wait until your design is almost finished to decide to certify or choose a program. At that point, you have fewer chances to improve performance, keep costs in line, and meet green program requirements. For all these reasons, it’s always better to design green from the start.
In the early planning stages of a project, you can consider certification options and requirements with the entire team—designers, engineers, construction managers, and trade contractors. Their input is critical to making the best decisions from the beginning of design until construction is complete.
Energy Efficiency by Design
Building orientation, structural systems, and mechanical design and installation are critical components that, when considered early in the process and with input from the entire team, can lower a property’s construction and operational costs.
Careful building orientation, window selection, and appropriate shading can take advantage of the heat from the sun, letting it in to heat space when desired and keeping it out and avoiding overheating during warm weather. Managing window placement can reduce heating and cooling loads, improve occupant comfort, and take advantage of natural light to reduce electrical loads. Limiting the amount of west- and east-facing glazing reduces excess heat in summer. South-facing glazing can be shaded in warm weather with moderate overhangs and allows winter sun to provide additional heat. North windows provide natural light without direct sunlight and, in moderate climates, don’t cause a severe energy penalty.
Multistory buildings require significant structural support, particularly at lower floors. These structural elements, whether wood framing or structural steel, displace space that would otherwise be used for insulation. Any redundant structural elements that can be eliminated reduce costs, and the insulation that replaces them generally doesn’t cost any extra. Since most energy codes now require steel-framed buildings to install continuous exterior insulation, consider replacing standard insulation in framed walls with more exterior rigid boards. This will improve performance and eliminate thermal bridging.
A building oriented to maximize the sun’s energy and designed and built with high-performance insulation will require smaller HVAC systems to heat and cool. Those systems should be sized for the reduced load and placed inside the building envelope to reduce their heat gain and loss, and they can be distributed with shorter duct runs. In most cases, there’s no need to put supply registers near windows and doors at the building perimeter. Instead, shorter interior duct runs can adequately condition a tightly sealed and insulated building. Fewer ducts can lower installation costs, and smaller systems have lower operating costs. In many cases, thoughtful choices in system size and distribution efficiency will provide more energy savings than high-efficiency equipment while reducing installation costs.
Additional issues to consider in completing the green-certification process include ventilation requirements, water efficiency, lighting and appliances, and indoor air quality and its effect on occupant health. I will address each of these topics in upcoming articles in this green building series.
Carl Seville is a green builder, educator, and consultant on sustainability to the building industry. He is a HERS rater and holds the LEED AP Homes and Green Rater designations. During his 25 years as a remodeling contractor, Seville led the development of the EarthCraft Renovation green building certification program and supervised its pilot projects. He certifies single- and multifamily buildings under all green programs. Visit his website at www.sevilleconsulting.com.