ASHRAE Journal - February 2011 - 27

The Problems
The problems are presented in order from least to most frequent.

8. Inadequate billing analysis: 57% of audits.
For an audit to be classified as having this problem, it must be missing at least three out of four of the following: monthly summaries of fuel bills (at least one year); a true-up of bills to the energy audit model; projected savings being a reasonable fraction of total annual use; and some form of benchmarking (even if simple).

10. Inadequate review: 30% of audits.
Inadequate review was defined as three or more obvious mistakes, other than mistakes in calculation. Examples included sections in a report that were duplicated within the same report; a reference to heat pump thermostat savings in a building that actually has a gas furnace; 1 cfm being defined as the air in a basketball (presumably meant to be 1 cubic foot); and electric air conditioning savings shown in units of therms. We speculate that inadequate proofreading may not be solely the fault of the energy auditor, but rather may be the result of inadequate supervision and review. In our experience, energy audits are frequently performed by entry-level staff. It is critical that senior staff participate actively at every stage, including planning, field investigation, and review. A solid quality control plan includes review of the building description and proposed list of improvements to be evaluated, before modeling begins. A model review is also important, to ensure that the model matches the building description, that assumptions are reasonable, and that results have been interpreted correctly. And finally, review of the final report is vital.

7 (tie). Poor building description: 60% of audits.
Again, the bar was set fairly low. We sought only a basic description of at least five components of a building from among 10 possible components: wall/ roof (either R-values or a simple description); infiltration; ventilation; heating/cooling; lighting; appliances/plug-loads; domestic hot water; motors/drives; windows; and controls. The description sought was also minimal. For example a window description such as “double-pane” was deemed sufficient to meet the criterion of having been described. The purposes of a building description are many, including allowing review of the energy audit by senior staff and by the client, as well as regulatory or funding agencies, allowing the insightful development of improvements, and ensuring program compliance for audits occurring within the context of large energy programs. A poor building description also can be used to identify auditor weaknesses, insufficient time spent in the building, and other systemic problems with the audit. In our experience, a poor building description is often associated with a greater likelihood of missed improvements (see below).

9. Overestimated savings: 53% of audits.
The bar was set high for defining overestimated savings. An audit had to have an improvement with savings more than twice as high as reasonable (or no savings given along with claims of payback in less than one year). Overestimated savings arise from poor modeling, incorrect measurements or assumptions, or not accounting for interactive effects between improvements. For savings to be overestimated, either energy use by existing equipment is overestimated, or energy use by proposed equipment is underestimated, or a combination of the two. Our experience has shown that the energy auditor can sometimes overenthusiastically bias assumptions to nudge an improvement toward “recommended.” Examples included residential lights presumed to operate more than eight hours per day (research shows that residential lighting use averages under three hours/day)1 and heating controls that presume a 10°F (6°C) reduction in indoor temperature. Because of the high threshold needed for an audit to qualify as having overestimated savings, the number of audits with overestimated savings that might still be measurable in terms of undelivered savings in utility bills is likely a good bit higher than 53%. The separate problem of underestimated savings, which could result in unwarranted rejection of an improvement, was not examined because of the likely exclusion of such improvements from the reviewed audits.
February 2011

6 (tie). Low (or missing) installed costs: 60% of audits.
The criterion for this problem was for a cost estimate to be less than half what might be reasonable for a specific improvement. Underestimating installed costs can be a serious mistake, as the installed cost estimate in an energy audit often serves as the owner’s initial budget for implementation. When subsequent bid costs are received by the owner, and are higher than anticipated, we have found that there is a greater risk of the improvement being abandoned before implementation. Another risk is poor prioritization of improvements. An underestimated improvement might mistakenly be chosen for implementation instead of a more cost-effective improvement. Examples of underestimating included $62,000 to install more than 70 heat pump water heaters, and $2,000 to install 40 daylight controls. We recognize that installed costs are often overestimated, but such problems are not usually seen within the audit, as the improvement is falsely rejected on the basis of overestimated costs.
ASHRAE Journal 27

ASHRAE Journal - February 2011

Table of Contents for the Digital Edition of ASHRAE Journal - February 2011