Green buildings often are assumed to be energy-efficient. However, a building's energy efficiency depends on the designer's and the owner's understanding and definition of the term.
Building energy efficiency is defined as a composite of the first, operating, and maintenance costs of a structure's predicted lifetime. It is difficult to obtain comparative numbers because historical data does not yet exist to make true comparisons. However, partial data that includes construction costs and a preliminary energy-cost analysis typically are available and would be a good indicator of energy-efficiency potential. With careful evaluation of green design variables, cost control, and smart building operation, truly energy-efficient building designs are possible.
People not intimately familiar with building design and operating efficiency take it for granted that a building classified as "green" will be energy-efficient and environmentally friendly. Proving design efficiency, however, is rather difficult. Programs that promote (or require) green designs but do not point out possible pitfalls are misleading.
More and more municipalities are making green-design compliance mandatory. Designers often jump on the bandwagon to secure commissions and promise designs that may not fulfill client expectations.
Let's separate building owners and developers who are pursuing green-building certification and willing to pay the price for more energy-efficient and sustainable buildings from those who promote green design and construction strictly to take advantage of numerous federal and local incentives, hoping for financial advantages. This column will focus on the first group of building owners/developers.
Purity vs. ProfitDuring the early 1980s, tax incentives for solar projects ended, as did the solar-building frenzy. The cost of continuous unsubsidized maintenance became unattractive to building owners, who no longer could afford to keep their systems in working order. One by one, solar panels disappeared and popular interest vanished. Currently, only a few of those installations are operational. A similar future could be awaiting green designs.
The original goal of the green movement was pure and straightforward: promote energy-efficient, environmentally friendly, and sustainable designs. As various green-building organizations become more profit-centric, the green movement’s purity is eroding and in danger of being lost.
Energy efficiency is being hotly debated in the buildings industry. Sadly, building designers are looking only at green-building guidelines in the hopes of earning "points." This attitude is reflected in poorly designed, monstrous mechanical, plumbing, and lighting systems that clearly are too difficult to build and maintain, with no justification of first costs or operating expenses.
Is Green Synonymous With Efficiency?Are green buildings more energy-efficient than their non-certified and, therefore, "non-green" counterparts? Building identical facilities that operate simultaneously side-by-side is almost impossible, as is measuring energy use, controlling environments, and evaluating results in exactly the same manner at both locations.
Laboratory conditions would be difficult to create or maintain for the precise evaluation of large-scale, living structures.
The Chicago chapter of the U.S. Green Building Council developed a reliable and comprehensive study on building energy efficiency that involved 25 built projects in Illinois.1 Seventeen participants submitted whole-building energy data; energy users were able to be quantified individually by project.
Because of the variety of occupancy types, total energy-use comparison is difficult, according to the study. It warns that "extrapolating the results from this data set to represent the performance of all LEED projects … is not valid."
Projects that focused on possible energy-performance points functioned better than other facilities. However, some LEED-certified buildings performed worse than non-certified buildings.
One interesting piece of data can be deduced clearly from the report without extrapolation: The baseline computer-simulation performances always predicted a better energy-use intensity (expressed in thousands of British thermal units per square foot per year) than the actual measured data. Therefore, it is clear that designers should be cautious about relying on results obtained from a preliminary computer simulation when quoting future performance data. This is just one reason why building professionals cannot rely solely on computer simulation.
ConclusionThe problem arises when designers (and building owners) get carried away, concentrating only on-point collection. These projects tend to end up with excessive costs and unjustifiable energy expenses.
If building professionals cannot refocus on first cost, energy use, and maintenance cost, the progress made through energy-efficient-design concepts could be lost. While certain green-building publications promise requirements on submitting operational data for post-occupancy certification, it is unclear how that data will be used. Will a building's certification be withdrawn if the certifying organization is not happy with future results? What are the liability implications of such reversals? These issues will be discussed in parts 2 and 3 of this series.
- U.S. Green Building Council Chicago Chapter. (2009). Regional green building case study project: A post-occupancy study of LEED projects in Illinois. Chicago: USGBC Chicago Chapter.
- Bezos, B. Green design 2010: Myths and perceptions. (n.d.). Retrieved from http://www.suncam.com/ continuing-education/100185.html
- Lstiburek, J. (2008, November). Why green can be wash. ASHRAE Journal, pp. 28-36.
- Qualk, J., & McCown, P. (2009, October). The cost-effectiveness of building 'green.' HPAC Engineering, pp. 18-23.
Stephen J. Vamosi, PE, is principal and chief executive officer of Intertech Design Services, an architecture and engineering firm specializing in the design of commercial, medical, educational, and retail buildings (www.intertechdesign.net). He also is a professor emeritus for the University of Cincinnati and a member of the American Society of Heating, Refrigerating and Air-Conditioning Engineers.