| Authors: |
Brad Acker, Kevin Van Den Wymelenberg, University of Idaho Integrated Design Lab - Boise |
| Published: |
May 2010 |
| Links: |
Pre-print pdf | Online publication |
| Abstract: |
A variety of technologies exist to save energy in buildings and new processes have been developed to reduce construction costs, improve delivery times and deliver projects that meet owner requirements. Specifically the building commissioning (Cx) process, such as outlined by ASHRAE Guideline 0-2005, has been shown to save 16% median whole-building energy savings in existing buildings and 13% in new construction (Mills, 2009). In addition, non-energy related items were shown to provide even greater financial benefits. Of the deficiencies found in the commissioning process, 62% were reported to result in higher repair costs, 10% resulted in shortened equipment life, 5% were related to productivity effects and 10% were related to increased energy consumption (Mills, 2009). The commissioning process cannot solely guarantee energy savings, but a comprehensive commissioning guideline ensures quality in the installation and setup of systems so they will be capable to operate as designed and provides functionality originally specified by the owner. Energy efficiency measures (EEM) such as air-side economizers, demand control ventilation (DCV), photo controlled lighting systems and energy management systems (EMS) are a few EEM that save energy. Air-side economizers have gained popular acceptance; one study found savings in both energy and sick leave of employees due to increased fresh air (Frisk, et. al., 2004). With regard to DCV one generalized study (Roth et al. 2005) found a 10% savings in both heating and cooling energy. Specifically, this study reported a 6-22% cooling savings, which depended on building location and building type. Furthermore savings are maximized when DCV systems are used in conjunction with air side economizers. Daylight photo control systems are one EEM which have been plagued with estimated energy savings varying from measured savings. Variance has been found both above and below modeled values; user interaction with such systems may account for wide variances. One study reported zero energy savings in 52% of the space studied and the 48% of the space that did save energy, saved only 53% of what was predicted via modeling (Heschong, Howlett, McHugh, & Pande, 2005). EMS are often used as a back bone to control the above EEMs, among many others. EMS have been shown to be invaluable in the daily operations of high performance buildings and providing energy saving is only one aspect of EMS. Because EMS control subsystems such as the ones mentioned above savings are confounded and difficult to cite separately, building scheduling is a key aspect of EMS and provides measureable energy savings. According to Hatley et al. (2005), scheduling features of an EMS can save at least 15% of total energy costs. All of these ever-evolving technologies require careful attention in the commissioning process to deliver the energy saving modeled or expected. This paper will outline some key aspects of the commissioning process which have been found to be underutilized and specific EEM issues to be anticipated and avoided in the installation and operation of high performance buildings. This paper relies largely on the findings of work performed at the University of Idaho, Integrated Design Lab-Boise as a result of several field studies during 2009 and highlighted in studies published in 2010 (Acker Van Den Wymelenberg A-E). |
