Buildings make up 40% of total U.S. energy consumption (including two-thirds of the country’s electricity) and 16% of total U.S. water consumption. They are responsible for 40% of all material flows and produce 15%– 40% of the waste in landfills, depending on the region. Clearly, large-scale improvements in resource productivity in buildings would have a profound effect on national resource consumption.

Reducing energy use in buildings saves resources and money while reducing pollution and CO2 in the atmosphere. It also leverages even greater savings at power plants. For instance, if electricity is coming from a 35%-efficient coal-fired power plant and experiencing 6% transmission line losses, saving a unit of electricity in a building saves three units of fuel at the power plant.

How Much Space is Required?

One of the key ways of reducing resource consumption and cost is to evaluate first whether a new building really needs to be built. Renovating an existing building can save money, time, and resources, and can often enable a company (or a family, if it is a residential building) to be located in a part of town with existing infrastructure and public transportation, enhancing convenience and reducing sprawl.

Next, if a new building is required, it should be sized only as large as it really needs to be. Smaller buildings require fewer building materials, less land, and less operational energy.

The American cultural assumption is that we should buy (or lease) as much square footage as we can afford. In the residential sector for instance, the average new house size has steadily increased from 983 square feet in 1950 to 2,349 square feet in 2004, while the average number of people per household has shrunk from 3.38 in 1950 to 2.60 in 2004. Yet smaller houses and commercial buildings allow the budget to be spent on quality, rather than what may be underused quantity.

Reducing the Energy Needed

In buildings, great opportunity lies in simple design solutions that intelligently respond to location and climate. For instance, for most North American sites, simply facing the long side of a building within 15 degrees of true south (and using proper shading to block summer, but not winter sun) can save up to 40% of the energy consumption of the same building turned 90 degrees.

Attention to making the building envelope (exterior walls, roof, and windows) as efficient as possible for the climate can also dramatically reduce loads, especially in “skindominated” buildings (residences and other small buildings). For this type of building, optimal sealing, insulation, and radiant barriers, combined with heat-recovery ventilation, can reduce heat losses to less than half that of a building that simply meets code.

Heat Load

Besides entering through the building envelope, heat can also be generated inside the building by lights, equipment, and people. Especially in large, “load-dominated” buildings, many of which tend today to be air-conditioned year-round, installing efficient lighting and appliances (which emit less heat) will significantly reduce the building’s cooling load.

Using daylight as much as possible will reduce cooling loads even more, because daylight contains the least amount of heat per lumen of light. (Incandescent lights are the worst—and thus the least “efficient;” they are basically small heaters that happen to produce a bit of light.)

Integrated Design

Integrated design makes use of the site’s natural resources, technological efficiency, and synergies between systems.

Once the building envelope is efficiently designed to reduce heat flow, natural heating and cooling methods can be used to greatly downsize, or even eliminate, fossil fuel-based mechanical heating and cooling systems. Techniques include daylighting, solar heating, natural ventilation and cooling, efficient and right-sized HVAC systems, and utilization of waste heat.

Renewable Energy

After all practical steps have been taken to reduce energy loads, appropriate renewable energy sources should be evaluated. These include wind, biomass from waste materials, ethanol from crop residues, passive heating and cooling, photovoltaics, geothermal, tidal, and environmentally benign hydro (including micro-hydro) technologies.

Third-Party Commissioning

Building commissioning—independent assessment of systems to ensure that their installation and operation meets design specifications and is as efficient as possible—can save as much as 40% of a building’s utility bills for heating, cooling, and ventilation, according to Lawrence Berkeley National Laboratory. The commissioning agent ideally gets involved with the project at its outset.

Throughout the life of the building, ongoing, regularly-scheduled maintenance and inspection as well as formal “re-commissioning” ensure proper, planned performance and efficiency of the building and its mechanical systems.

Related Articles

• Controlling Heat Transfer in Green Buildings
• Limiting Heat Loss Through Windows
• Efficient Cooling Methods for Green Buildings

This article is an excerpt from the book Green Building: Project Planning & Estimating which can be purchased through the RSMeans Bookstore.

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