How Well Are Green Buildings Performing?
With the growing interest in green building, many studies have been conducted to evaluate the performance of sustainable buildings that were constructed over the past two decades. It is important to note the advantages and disadvantages of past projects in order to learn the most effective methods of green building. The effectiveness of sustainable buildings can be measured by analyzing the scores given to them by green building rating systems and by their occupants.
In order to evaluate the progress of green building in the United States, a particular study looked at the scores given to buildings by the green rating system LEED. This study involved 490 certified buildings, built from 2002 through 2009, selected from the US Green Building Council’s database. Of the buildings chosen, 52% were commercial and 30% while the rest were classified as “other”. Using the information collected from the GBC database, an analysis was conducted to see how “green” the average certified building is. This was done by noting the amount of points granted to each building. Figure 1 illustrates the percentage of earned points in each LEED category for each level of certified buildings. In the category sustainable sites, the assessed buildings on average received fewer than 50% of the available points. It is important to note, however, that site selection is limited as a result of municipal policies and previous land uses. The buildings also received an average of 38%, 56%, 62%, 40%, and 66% in the categories energy and atmosphere, indoor environmental quality, water efficiency, material and resources, and innovation and design respectively. From this study it was deduced that although energy performance is considered the most important in green building, it has been difficult to effectively achieve thus far. This is a result of the lack of preparedness of engineers and construction workers regarding green building (Berardi, 2012). In another study conducted, the utility billing data of 21 federal buildings was examined to determine the energy efficiency of the buildings. Out of the 17 possible points available in the energy efficiency category of LEED-NC, the buildings received an average score of 5.6. In addition, out of the 12 buildings with ENERGY STAR scores, only 4 qualified to receive ENERGY STAR certification (Diamond, Opitz, Hicks, Von Neida, and Herrera, 2011). The results from this study further prove that the energy performance of recently built green buildings falls below expectations. Since the concept is fairly new, engineers and construction workers must research about how to include green building concepts in their designs.
Figure 1: Earned Points in LEED Categories by LEED-Certified Buildings, Source: Berardi, U. (2012). Sustainability Assessment in the Construction Sector: Rating Systems and Rated Buildings. Sustainable Development, 20(6), 411-424.
To further assess the performance of recently constructed green buildings, occupants have been asked to rate their experience in these buildings. In a study conducted by the New Building Institute, it was found that 30% of LEED-rated buildings perform better than expected while 25% perform worse than expected. A handful of LEED buildings have also been reported to have serious energy consumption problems. When looking at post-occupancy user evaluations, it is important to note that there are various factors that could be affecting the occupants’ opinions. Problems caused by technical failures, too high expectations, and inappropriate use of technologies are a few of these factors (Hauge, Thomsen, and Berker, 2011). A study conducted by the Center for the Built Environment involved surveying occupants of 215 buildings, classified as either conventional or green, in the United States, Canada, and Finland on the indoor environmental quality of the building they used. Occupants were asked to rate their satisfaction from a scale of -3, meaning very dissatisfied, to 3, meaning very satisfied. Table 1 shows the results from the conducted survey. Overall, occupants in LEED-certified buildings seemed to be on average satisfied with the office furnishings, thermal comfort, air quality, cleaning and maintenance, and workspace. In comparison to the conventional buildings, the LEED-certified buildings received an overall satisfaction rate of 1.47 to 0.93 (Abbaszadeh, Zagreus, Lehrer, and Huizenga, 2006). In another study, workers at a Canadian company were asked to evaluate their satisfaction with the conventional building they were initially working in and with the new green building they recently moved into. They were specifically inquired about the building design, work requirements, comfort, health, productivity, their knowledge of the building, their engagement with personal control, and their perceptions of organization culture. Occupants reported to be on average 36% more comfortable, 41% more healthy, and 73% either neutral or more productive in the green building. As for complaints, occupants reported that there was too much indoor noise and that indoor temperatures during the winter were low. Overall, however, it was concluded that the performance of the green buildings was better than that of the conventional buildings (Brown, Cole, Robinson, and Dowlatabadi, 2010).
Table 1: Survey Scores of Database Conventional and Green Buildings, Source: Abbaszadeh, S., Zagreus, L., Lehrer, D., & Huizenga, C. (2006). Occupant Satisfaction with Indoor Environmental Quality in Green Buildings. Center for the Built Environment.
Based on the studies conducted on recently constructed green buildings, it is evident that the implementation of the green building concept can still be improved on. Despite their inability to reach the desired level of energy saving, green buildings are still deemed to perform better than conventional buildings. Overtime the process of green building is expected to improve as the idea is further developed.
References
Abbaszadeh, S., Zagreus, L., Lehrer, D., & Huizenga, C. (2006). Occupant Satisfaction with Indoor Environmental Quality in Green Buildings. Center for the Built Environment.
Berardi, U. (2012). Sustainability Assessment in the Construction Sector: Rating Systems and Rated Buildings. Sustainable Development, 20(6), 411-424.
Brown, Z., Cole, R. J., Robinson, J., & Dowlatabadi, H. (2010). Evaluating user experience in green buildings in relation to workplace culture and context. Facilities, 28(3/4), 225-238.
Diamond, R., Opitz, M., Hicks, T., Von Neida, B., & Herrera, S. (2011). Evaluating the Energy Performance of the First Generation of LEED-Certified Commercial Buildings. Lawrence Berkeley National Laboratory.
Hauge, Å. L., Thomsen, J., & Berker, T. (2011). User Evaluations of Energy Efficient Buildings: Literature Review and Further Research. Advances in Building Energy Research, 5(1), 109-127.
