Residential energy auditors are accredited by the Building Performance Institute (BPI) or the Residential Energy Services Network (RESNET).
There are also some simplified tools available, with which a homeowner can quickly assess energy improvement potential. Often these are supplied for free by state agencies or local utilities, who produce a report with estimates of usage by device/area (since they have usage information already). Examples include the Energy Trust of Oregon program and the Seattle Home Resource Profile. Such programs may also include free compact fluorescent lights.
A simple do-it-yourself home energy audit can be performed without using any specialized tools. With an attentive and planned assessment, a homeowner can spot many problems that cause energy losses and make decisions about possible energy efficiency upgrades. During a home energy audit it is important to have a checklist of areas that were inspected as well as problems identified. Once the audit is completed, a plan for suggested actions needs to be developed.
New York City
In New York City, local laws such as Local Law 87 require buildings larger than 50,000 square feet (4,600 m2) to have an energy audit once every ten years, as assigned by its parcel number. Energy auditors must be certified to perform this work, although there is no oversight to enforce the rule. Because Local Law 87 requires a licensed Professional Engineer to oversee the work, choosing a well-established engineering firm is the safest route.
These laws are the results of New York City’s PlaNYC to reduce energy used by buildings, which is the greatest source of pollution in New York City. Some engineering firms provide free energy audits for facilities committed to implementing the energy saving measures found.
In Lebanon
Since 2002, The Lebanese Center for Energy Conservation (LCEC) initiated a nationwide program on energy audits for medium and large consuming facilities. By the end of 2008, LCEC has financed and supervised more than 100 audits.
LCEC launched an energy audit program to assist Lebanese energy consuming tertiary and public buildings and industrial plants in the management of their energy through this program.
The long-term objective of LCEC is to create a market for ESCOs, whereby any beneficiary can contact directly a specialized ESCO to conduct an energy audit, implement energy conservation measures and monitor energy saving program according to a standardized energy performance contract.
Currently, LCEC is helping in the funding of the energy audit study and thus is linking both the beneficiary and the energy audit firm. LCEC also targets the creation of a special fund used for the implementation of the energy conservation measures resulting from the study.
LCEC set a minimum standard for the ESCOs qualifications in Lebanon and published a list of qualified ESCOs[11] on its website.
Industrial energy audits
Increasingly in the last several decades, industrial energy audits have exploded as the demand to lower increasingly expensive energy costs and move towards a sustainable future have made energy audits greatly important. Their importance is magnified since energy spending is a major expense to industrial companies (energy spending accounts for ~ 10% of the average manufacturer’s expenses). This growing trend should only continue as energy costs continue to rise.
While the overall concept is similar to a home or residential energy audit, industrial energy audits require a different skillset. Weatherproofing and insulating a house are the main focus of residential energy audits. For industrial applications, it is the HVAC, lighting, and production equipment that use the most energy, and hence are the primary focus of energy audits.
Types of energy audit
The term energy audit is commonly used to describe a broad spectrum of energy studies ranging from a quick walk-through of a facility to identify major problem areas to a comprehensive analysis of the implications of alternative energy efficiency measures sufficient to satisfy the financial criteria of sophisticated investors. Numerous audit procedures have been developed for non-residential (tertiary) buildings (ASHRAE; IEA-EBC Annex 11; Krarti, 2000). Audit is required to identify the most efficient and cost-effective Energy Conservation Opportunities (ECOs) or Measures (ECMs). Energy conservation opportunities (or measures) can consist in more efficient use or of partial or global replacement of the existing installation.
When looking to the existing audit methodologies developed in IEA EBC Annex 11, by ASHRAE and by Krarti (2000), it appears that the main issues of an audit process are:
- The analysis of building and utility data, including study of the installed equipment and analysis of energy bills;
- The survey of the real operating conditions;
- The understanding of the building behaviour and of the interactions with weather, occupancy and operating schedules;
- The selection and the evaluation of energy conservation measures;
- The estimation of energy saving potential;
- The identification of customer concerns and needs.
Common types/levels of energy audits are distinguished below, although the actual tasks performed and level of effort may vary with the consultant providing services under these broad headings. The only way to ensure that a proposed audit will meet your specific needs is to spell out those requirements in a detailed scope of work. Taking the time to prepare a formal solicitation will also assure the building owner of receiving competitive and comparable proposals.
Generally, four levels of analysis can be outlined (ASHRAE):
- Level 0 – Benchmarking: This first analysis consists in a preliminary Whole Building Energy Use (WBEU) analysis based on the analysis of the historic utility use and costs and the comparison of the performances of the buildings to those of similar buildings. This benchmarking of the studied installation allows determining if further analysis is required;
- Level I – Walk-through audit: Preliminary analysis made to assess building energy efficiency to identify not only simple and low-cost improvements but also a list of energy conservation measures (ECMs, or energy conservation opportunities, ECOs) to orient the future detailed audit. This inspection is based on visual verifications, study of installed equipment and operating data and detailed analysis of recorded energy consumption collected during the benchmarking phase;
- Level II – Detailed/General energy audit: Based on the results of the pre-audit, this type of energy audit consists in energy use survey in order to provide a comprehensive analysis of the studied installation, a more detailed analysis of the facility, a breakdown of the energy use and a first quantitative evaluation of the ECOs/ECMs selected to correct the defects or improve the existing installation. This level of analysis can involve advanced on-site measurements and sophisticated computer-based simulation tools to evaluate precisely the selected energy retrofits;
- Level III – Investment-Grade audit: Detailed Analysis of Capital-Intensive Modifications focusing on potential costly ECOs requiring rigorous engineering study
Benchmarking
The impossibility of describing all possible situations that might be encountered during an audit means that it is necessary to find a way of describing what constitutes good, average and bad energy performance across a range of situations. The aim of benchmarking is to answer this question. Benchmarking mainly consists in comparing the measured consumption with reference consumption of other similar buildings or generated by simulation tools to identify excessive or unacceptable running costs. As mentioned before, benchmarking is also necessary to identify buildings presenting interesting energy saving potential. An important issue in benchmarking is the use of performance indices to characterize the building.
These indexes can be:
- Comfort indexes, comparing the actual comfort conditions to the comfort requirements;
- Energy indexes, consisting in energy demands divided by heated/conditioned area, allowing comparison with reference values of the indexes coming from regulation or similar buildings;
- Energy demands, directly compared to “reference” energy demands generated by means of simulation tools.
Typically, benchmarks are established based on the energy outlets (loads) within the building and are then further parsed into “base loads” and “weather sensitive loads”. These are established through a simple regression analysis of energy consumption and demand (if metered) correlated to weather (temperature and degree – day) data during the period for which utility data is available. Aggregate base loads will represent as the intercept of this regression and the slope will typically represent the combination of building envelope conduction and infiltration losses less losses or gains from the base loads themselves. For example, while lighting is typically a base load, the heat generated from that lighting must be subtracted from the weather sensitive cooling load derived from the slope to gain an accurate picture of the true contribution of the building envelope on cooling energy use and demand.