Wikipedia defines energy audit as:
An inspection, survey and analysis of energy flows in a building,…. to seek opportunities to reduce the amount of energy input ...while maintaining or improving human comfort....

Hyde-Stone Mechanical is happy to be able to provide this service for you, our customer.

An energy audit of a building 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 are strongly affected by window construction and quality of door seals such as weatherstripping. The goal of this exercise is 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. Further an audit may access building lighting and electrical uses to quantify electrical energy usage.

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, two or three-year period.

Some of the greatest effects on energy use are user behavior, climate, and age of the building. An energy audit may therefore include an interview of the building users 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, building may qualify for tax credits from governments and incentives for equipment and lighting changes from NYSERTA or National Grid.

Types of energy audit

 

Preliminary or Walkthrough audit
Typically, only major problem areas will be uncovered during this type of audit. Corrective measures are briefly described, and quick estimates of implementation cost, potential operating cost savings, and simple payback periods may be provided. This level of detail, while not sufficient for reaching a final decision on implementing a proposed measures, is adequate to prioritize energy-efficiency projects and to determine the need for a more detailed audit.

 

 

General audit
The general audit (alternatively called a mini-audit, site energy audit or detailed energy collecting more detailed information about facility operation and by performing a more detailed evaluation of energy conservation measures. Utility bills are collected for a 12 to 36 month period to allow the auditor to evaluate the facility's energy/demand rate structures and energy usage profiles. If interval meter data is available, the detailed energy profiles that such data makes possible will typically be analyzed for signs of energy waste. Additional metering of specific energy-consuming systems is often performed to supplement utility data. In-depth interviews with facility operating personnel are conducted to provide a better understanding of major energy consuming systems and to gain insight into short and longer term energy consumption patterns.
This type of audit will be able to identify all energy-conservation measures appropriate for the facility, given its operating parameters. A detailed financial analysis is performed for each measure based on detailed implementation cost estimates, site-specific operating cost savings, and the customer's investment criteria. Sufficient detail is provided to justify project implementation.

 

Investment-grade audit
In most corporate settings, upgrades to a facility's energy infrastructure must compete for capital funding with non-energy-related investments. Both energy and non-energy investments are rated on a single set of financial criteria that generally stress the expected return on investment (ROI). The projected operating savings from the implementation of energy projects must be developed such that they provide a high level of confidence. In fact, investors often demand guaranteed savings.
The investment-grade audit (alternatively called a comprehensive audit, detailed audit, maxi audit, or technical analysis audit) expands on the general audit described above by providing a dynamic model of energy-use characteristics of both the existing facility and all energy conservation measures identified. The building model is calibrated against actual utility data to provide a realistic baseline against which to compute operating savings for proposed measures. Extensive attention is given to understanding not only the operating characteristics of all energy consuming systems, but also situations that cause load profile variations on short and longer term bases (e.g. daily, weekly, monthly, annual). Existing utility data is supplemented with submetering of major energy consuming systems and monitoring of system operating characteristics.

 

 

Retro-commissioning or Existing Building Commissioning
Often over time a building’s use will change. An area that was once a large storage room become divided into partitioned offices or an area that once was used for a office staff is turned in an space with processing equipment. These changes do not reflect the original design and layout of the HVAC equipment. Occupants block ducts, add electric heaters or make other make-shift attempts to maintain comfort or process parameters. The intent of retrocommissioning is to correct the HVAC design to bring it back in line with the building current uses. The design is updated and fine tuned to provide the best combination controlling space parameter while minimizing building operating costs.

 

 

 

The commissioning process can be applied to existing buildings that have never been commissioned to restore them to optimal performance. Retro-commissioning is a systematic, documented process that identifies low-cost operational and maintenance improvements in existing buildings and brings the buildings up to the design intentions of its current usage.

 

 

 

Retro-commissioning typically includes an audit of the entire building including a study of past utility bills, interviews with facility personnel. Then diagnostic monitoring and functional tests of building systems may be executed and analyzed. Building systems are retested and remonitored to fine-tune improvements. This process helps find and repair operational problems. The identification of more complex problems are presented to the owner as well. A final report, recommissioning plan and schedule are then given to the owner.