ASHRAE Journal - October 2013 - 60

Column The Performance GaP
Leslie Beu

Lessons From Church Project
By LesLie Beu, associate memBer ashrae

Convincing decision-makers to spend money on energy and sustainability
strategies when designing a building or HVAC system can be difficult. This is
partly because building owners, investors, and lenders often lack confidence
because of the risk of the “performance gap,” a divergence between analyst
predictions and operational data.
Only two explanations exist for the discrepancy
between predicted energy performance and actual
energy consumption. Either the predictions were inaccurate from the beginning, or the building is under-performing. After investigating many new construction and
retrofit projects, five common pitfalls were identified
that contribute to the performance gap:
• Under-qualified team members;
• Poorly specified design details;
• Field installations errors;
• Poor communication; and
• Lack of accountability.
The case study discussed in this column is from a
real retrofit energy project (although some identifying
details have been made generic) that demonstrates how
the five pitfalls impacted this specific project.

Project Overview
A church in the Denver-metro area had equipment so
old it was barely operational. The owner knew it needed
new equipment to replace failing systems.
The church decided to go beyond the lowest first-cost
solution and invest more money in upgraded systems
based on projected energy savings and life-cycle cost
projections. The proposed higher efficiency boilers,
chillers, and overhauled control system also promised
incremental annual savings of $19,389 and an incremental ROI of 40% compared to the necessary lowest
first cost scope. Life-cycle costs are shown in Figure 1.

Problems
After initial project scoping, energy savings calculations
and rebate estimations were completed, the energy team
planned to stay involved in the design process, submittal
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approval, and sequence of operations parameters.
However, the project timeline was accelerated. During the
rush, many errors occurred, such as mechanical drawings
being quickly created without site verification of the existing piping and equipment details.
Since the existing system was not well understood by
the mechanical engineer, the resulting mechanical construction documents were not applicable to the system.
Furthermore, to reduce costs at the customer’s request,
existing pneumatic valves would be left instead of being
replaced with new valves. This “value engineering”
change was not reflected in any updated drawings.
The installers began installing new systems before
final update drawings were completed or approved.
Since the drawings did not show a system that actually
could be installed, the construction team implemented
the piping and pumping configuration as they usually
did. Unfortunately, the team didn’t know about the performance-critical piping changes for the new system.
The installed configuration was functional, but
resulted in reduced efficiency and capacity. The new
piping configuration was designed based on upgraded
control valves with different internal components and
fail-safe action. Therefore, leaving the existing pneumatic valves caused problems that were not foreseen
during the isolated value engineering discussion.

Investigation
After the new mechanical equipment, controls, and
associated piping were implemented, the energy team
was brought in to verify operation. None of the systems
were installed as intended. To make matters worse,
Leslie Beu is an energy engineer at Tolin Mechanical in Denver.

ASHRAE Journal - October 2013

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