Energy audit
An energy audit is an inspection survey and an analysis of energy flows for energy conservation in a building. It may include a process or system to reduce the amount of energy input into the system without negatively affecting the output. In commercial and industrial real estate, an energy audit is the first step in identifying opportunities to reduce energy expense and carbon footprint.
Principle
When the object of study is an occupied building then reducing energy consumption while maintaining or improving human comfort, health and safety are of primary concern. Beyond simply identifying the sources of energy use, an energy audit seeks to prioritize the energy uses according to the greatest to least cost-effective opportunities for energy savings.Home energy audit
A home energy audit is a service where the energy efficiency of a house is evaluated by a person using professional equipment, with the aim to suggest the best ways to improve energy efficiency in heating and cooling the house.An energy audit of a home may involve recording various characteristics of the building envelope including the walls, ceilings, floors, doors, windows, and skylights. For each of these components the area and resistance to heat flow is measured or estimated. The leakage rate or infiltration of air through the building envelope is of concern, which can be affected by window construction and quality of door seals such as weatherstripping. This exercise aims to quantify the building's overall thermal performance. The audit may also assess the efficiency, physical condition, and programming of mechanical systems such as the heating, ventilation, air conditioning equipment, and thermostat.
A home energy audit may include a written report estimating energy use given local climate criteria, thermostat settings, roof overhang, and solar orientation. This could show energy use for a given time period, say a year, and the impact of any suggested improvements per year. The accuracy of energy estimates are greatly improved when the homeowner's billing history is available showing the quantities of electricity, natural gas, fuel oil, or other energy sources consumed over a one or two-year period.
Some of the greatest effects on energy use are user behavior, climate, and age of the home. An energy audit may therefore include an interview of the homeowners to understand their patterns of use over time. The energy billing history from the local utility company can be calibrated using heating degree day and cooling degree day data obtained from recent, local weather data in combination with the thermal energy model of the building. Advances in computer-based thermal modeling can take into account many variables affecting energy use.
A home energy audit is often used to identify cost effective ways to improve the comfort and efficiency of buildings. In addition, homes may qualify for energy efficiency grants from central government.
Recently, the improvement of smartphone technology has enabled homeowners to perform relatively sophisticated energy audits of their own homes. This technique has been identified as a method to accelerate energy efficiency improvements.
In the United States
In the United States, this kind of service can often be facilitated by:- Public utility companies, or their energy conservation department.
- Independent, private-sector companies such as energy services company, insulation contractor, or air sealing specialist.
- State energy office.
Where to look for insulation recommendations:
- Local building inspector's office.
- Local or state building codes.
- US Department of Energy.
- Your local Builders Association
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. 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 and 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 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 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 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. 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 buildings. Audit is required to identify the most efficient and cost-effective Energy Conservation Opportunities or Measures. Energy conservation opportunities can consist in more efficient use or of partial or global replacement of the existing installation.
According to the audit methodologies developed in IEA EBC Annex 11, by ASHRAE and by Krarti, the main components 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.
Generally, four levels of analysis can be outlined :
- Level 0 – Benchmarking: This first analysis consists in a preliminary Whole Building Energy Use 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 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.