Building owners are constantly looking for opportunities to conserve energy and reduce operating costs, especially in the current economic environment. A building energy audit is the first step to understand where energy is being consumed and how it can be minimized moving forward.
Prior to beginning the audit, the auditor meets with the building owner, facility maintenance personnel, and other affected parties to ensure common goals are established and that necessary building personnel will be available during the audit. At this time, the auditor makes the initial data request, typically consisting of building diagrams and a minimum of two years of utility data. An inventory of on-site mechanical equipment, associated maintenance agreements, and any original equipment documentation is also helpful.
Certain audit steps are performed regardless of the building’s size, purpose, or usage patterns. When necessary, the scope of the audit can be modified to meet the client’s specific needs.
Prior to the site visit, the auditor determines how much energy the building uses for all energy sources through analysis of the aforementioned utility data. Calculation of the Energy Utilization Index (EUI) in BTU/square foot/year converts all energy usage into a common value. If comparison data is available, this allows the auditor to understand the potential for improvement by comparing the subject building to an array of data from similar buildings. Comparison data typically consists of government collected data (CBECS) which is provided via an online database for comparison purposes. Additionally, the auditor will calculate the base load of the building, review building plans, and look for irregular patterns of energy usage and possible causes. This provides insight to the auditor prior to the site visit.
Next, the site visit is conducted by the auditing team and the building’s maintenance staff, if needed. Detailed measurements are captured during the visual inspection, including square footage and window sizes in order to calculate the building’s average R-value. Additionally, an infrared thermal imaging scan of the building envelope reveals deficient insulation and/or air infiltration. These measurements and observations allow calculation of the value of any recommended building envelope improvements.
HVAC systems are visually inspected, inventoried, and might have their ductwork tested for leakage or pressure issues. Lighting fixture counts and locations are documented, lamp types and wattage are gathered, and indoor light readings are taken to determine the necessary lighting changes. If considerable outdoor lighting is being used, outdoor light readings are taken at night to find areas being over or under illuminated.
If the building uses significant refrigeration, this equipment is evaluated for proper operation and/or possible replacement. All other energy intensive components such as domestic hot water equipment, motors, etc. are also evaluated for possible energy savings and/or replacement. Often, the audit uncovers simple operational issues which can provide significant savings.
Once all necessary onsite data is collected and observations are made, the auditor has a wide variety of simulation tools to model the building’s energy usage. Once fine tuned, the auditor can model suggested improvements to understand their effect and calculate the value of these improvements so the list of recommendations can be prioritized based on payback period.
Finally, the auditor creates a detailed report to effectively communicate the audit results to a varied audience of clients from maintenance personnel to the owner of the building.
As a result of the audit, common recommendations typically include interior lighting retrofits and/or de-lamping of existing fixtures, HVAC upgrades, and insulation upgrades performed in conjunction with air sealing. Recommendations should be made with the understanding of how each interacts with the others from an energy savings, safety, and operational aspect.
Written by Dallas Gamble, Green Summit Consulting