Types of Energy Audits
I have talked to many who claimed that they conduct energy audits–they may have thought they did, but they did not conduct energy audits. An energy audit by an electrical contractor will not likely cover all energy consuming equipment. For example, it is likely that they will miss anything building envelope or boiler related, as they will focus only on those items that might generate revenue for their company: namely transformers and lights. These limited scope type of audits only serve to help the contractor, and are a disservice to both the customer and the industry, as the concept “energy audit” loses value in the eyes of the customer.
Because there was so much variance in the industry as to what exactly composed an energy audit, ASHRAE kindly stepped in and defined varying degrees of energy audit rigor. These different levels of audits are now called ASHRAE Level 1, ASHRAE Level 2 and ASHRAE Level 3 audits.
Some buildings don’t require hundreds of hours of engineering time, and a smaller audit will suffice, whereas for other buildings, the additional time and analysis is well worth the investment. A rightly sized energy audit will provide the right balance between audit cost and value of the audit.
The ASHRAE Level audits are recommendations. They are not law. You can always pick and choose what they want and don’t want in the audit. What is most important is that you get value for your money. If you spend $10,000 on an ASHRAE Level 2 audit that finds energy savings potential of $5000, then you overpaid for the audit, and probably should have gotten an ASHRAE Level 1 audit.
Preliminary Energy Use Analysis
All three levels of audits require a Preliminary Energy Use Analysis which involves the following:
- a site visit to assess the building and energy consuming equipment
- analysis of the utility bills to determine whether savings can be had by changing the utility rate
- a summary of utility bill data
- calculation of the energy use intensity (EUI)
- benchmarking to compare the site’s energy usage to that of similar sites in the same region
- estimate of the energy and costs saved if the building met an energy use intensity target
ASHRAE Level 1: Walk-through
The ASHRAE Level 1 audit is walk-through audit that will identify energy efficiency measures (EEMs) while limiting the necessary engineering time and costs to produce the report. The estimated savings and costs associated with each measure are of rough order magnitude. The brief report focuses on low-cost and no-cost measures, although capital measures are identified when found. The report also includes a summary of utility data, the estimation of savings associated with a rate change, the calculation of the energy use index, benchmarking, and targeting.
A small building will use very little energy, and will likely contain very little energy savings potential. For these small buildings, an ASHRAE Level 1 audit should suffice. Conducting more advanced audits on these small buildings may not be the most feasible option.
We often perform ASHRAE Level 1 audits for clients who are seeking LEED-EB status. ASHRAE Level 1 audits are required as a prerequisite to attain LEED-EB status.
ASHRAE Level 2: Energy Survey and Analysis
The ASHRAE Level 2 audit is more detailed and requires proficiency and thought to create a quality audit report. The Level 2 audit includes a complete description of the facility, including an equipment inventory, an energy balance, detailed energy savings and costs associated with each low-cost and not-cost measure, financial analysis of each recommended measure, identification and rough estimates of capital project costs and savings, and a recommended measurement and verification plan for each recommended measure.
The Level 2 audit is the most likely type of energy audit for larger buildings. The Level 2 audit balances the need for engineering rigor with the need to keep auditing cost effective. The additional accuracy afforded by the Level 3 audit may not be worth the additional cost.
We often perform ASHRAE Level 2 audits for clients who are seeking LEED-EB status. ASHRAE Level 2 audits are worth 2 points (LEED-EB Credit 2.1, Option B) and are sometimes selected by our clients as it is less expensive than Retro-Commissioning (LEED-EB Credit 2.1, Option A).
ASHRAE Level 3: Detailed Survey and Analysis
ASHRAE Level 3 audits are designed to provide additional engineering rigor for more expensive capital projects where risk is less tolerated. In these audits, trend logs and data loggers are used to better understand how the buildings react to changes in ambient conditions and occupancy. Calculations for HVAC measures are done with hourly simulations. Detailed costing estimates are provided, as are life cycle cost assessments. Typically a scope of work and schematics are provided with the audit so that the contractors installing the measures understand exactly what is to be installed. The reports contain more detailed descriptions of the measures.
Level 3 audits are sometimes called Investment Grade Audits (or IGAs). These audits are typically done as part of a performance contract.