ASHRAE Journal - July 2024 - 50

2024 ASHRAE TECHNOLOGY AWARDS CASE STUDY
1
ST
has changed signifi cantly. While routine
maintenance had replaced the AHU, which
was operating per its original sequence, no care
had been taken to ensure downstream zones applied
schedules. Working with facility operations, the team
discovered 50% of spaces downstream operated 8/5,
though per original programming, they were running
24/7. To remedy this, schedules were tailored to each
area to accomplish signifi cant savings. This went beyond
the recommissioning task of ensuring the AHU operated
per design. Instead, modern design techniques were
applied to existing systems at minimal cost, saving
money and reducing carbon footprint.
INDOOR AIR QUALITY
To optimize ventilation, all major existing airhandling
systems were surveyed to track and observe
the air handler outside air dampers' operation. Typical
to 1960s-era hospital buildings, many patient areas
were served by 100% outdoor air units, resulting in
over-ventilation of the existing building, far exceeding
code minimums from ASHRAE Standard 62.1 and even
ASHRAE Standard 170 . In some cases, existing systems
were far exceeding ventilation rates originally intended
As an example, one air handler had ventilation
dampers that had been manually adjusted but were
no longer controlled by the building automation
system. This led to the AHU operating far above the
designed minimum outdoor air rate. Identifying and
correcting this issue led to a nearly $10,000/yr savings.
The environmental quality in this area had also been
signifi cantly affected by the inability to control humidity
and temperature during summer and winter. By
fi xing this issue, the system's overall effectiveness also
improved, as well as its ability to maintain optimal
occupant conditions.
Our survey also indicated ventilation in surgery suites
and critical care areas was double the recommended
amount in many cases. These systems were revised to
still exceed code and maintain a high degree of IAQ
while substantially reducing overall energy use. Many
areas are still over-ventilated and were identifi ed as
options for future infrastructure projects, aiming to
include energy recovery systems or return air, as code
allows, to provide additional energy savings. All energy/
money saving measures conformed to current codes and
ensured patient health and safety fi rst.
50
ASHRAE JOURNAL ashrae.org J U LY 2 0 2 4
ENERGY EFFICIENCY AND COST
At the end of Lourdes Hospital's retro-commissioning
process, more than 27 low- and no-cost changes had
been implemented across both the Lourdes Hospital
facility and the adjacent Nemer Medical Offi ce Building
(MOB). Energy was tracked via utility bills and totaled
across the two facilities. The process saved nearly
7% energy use in the facility's fi rst year of operation,
dropping the facility's energy use intensity (EUI)
from 252 kBtu/ft2·yr to 234 kBtu/ft2· yr (2862 MJ/m2·yr
to 2657 MJ/m2·yr). In the Nemer MOB, energy use
due to retro-commissioning fell 8%, decreasing EUI
from 137 kBtu/ft2·yr (1556 MJ/m2·yr) to 126 kBtu/ft2·yr
(1431 MJ/m2·yr). The energy savings equated to an
adjusted dollar savings of over $200,000 dollars
annually. This more than paid for the cost of the retrocommissioning
effort in the fi rst year alone.
While the project resulted in an immediate energy
impact with limited investment, the project team did
not disregard the potential impact of replacing some
older systems as funds become available. As part of the
retro-commissioning project, the effi ciency of existing
systems was assessed. Next, a prioritized list weighing
the systems with the highest energy savings potential
was generated, including the central utility plant and
several older more energy-intensive HVAC systems. The
facility team will use this list to develop a roadmap for
future infrastructure dollars.
ENVIRONMENTAL IMPACT
The existing facility reduced its carbon footprint by
more than 807 metric tons per year. Also, though no
dedicated water meter was available, energy modeling
of these impacts revealed a cooling tower water
savings of 1,045,000 gallons (3 955 755 L). Buoying
these impressive results is the fact that carbon-heavy
construction was unnecessary to accomplish them.
In sum, this project was a rare triple-win. First, the
client, with minimal investment, was able to achieve
signifi cant energy savings with a less than one year
payback. In addition they were able to make an
impactful reduction in energy use, meeting their moral
imperative to improve the health and well being of the
communities that they serve. And fi nally, by focusing
engineering innovation on the existing systems this
project highlights and pushes forward the opportunity
for engineering advancement on existing systems. 
http://www.ashrae.org
ASHRAE Journal - July 2024

Table of Contents for the Digital Edition of ASHRAE Journal - July 2024
