ASHRAE Journal - September 2024 - 68

2024 ASHRAE TECHNOLOGY AWARDS CASE STUDY
2
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façades in all classrooms, administration areas
and corridors other than the main building
atrium skylight for automatic artifi cial lighting
dimming according to the daylight use.
DOMESTIC HOT WATER SYSTEM
The domestic hot water system is composed of an
underground HWP with three different systems:
System 1-laboratories, cleanrooms and dressing room
(showers), composed of four storage tanks (106 ft3 [3 m3]
each), with a hybrid heating system providing 40% of
daily consumption through solar panels, combined with
the heat recovery system from CWP and instantaneous
natural gas heaters as backup; System 2-kitchens,
composed of two natural gas boiler heaters with
storage tanks (106 ft3 [3 m3] each), which supply hot
water through a dedicated pumping loop; System 3-
HVAC, composed of a dedicated heating system of two
direct fi red gas heaters (142 tons [500 kW] of nominal
capacity), which supply hot water for the AHUs.
DOMESTIC HOT WATER ENERGY EFFICIENCY
Each hot water loop (Systems 1, 2 and 3) with recycling
pumps has automatic monitoring and controls
integrated in the BMS, and heaters were in accordance
with Standard 90.1-2010 minimum effi ciency. Each hot
water loop piping has thermal insulation according to
Standard 90.1-2010 Section 7.4.3.
ENERGY MODELING
Energy performance analysis was conducted according
to procedures presented in Appendix G of Standard
90.1-2010. The reference building (baseline model) was
compared with the proposed model. Building systems
strategies described contributed to the project's whole
energy performance (Figure 1 ). The proposed HVAC
system is 9.1% more energy effi cient than the baseline,
the lighting system composed of LED lighting fi xtures
resulted in 32.4% less consumption than the Standard
90.1-2010 light power density and controls, and the
domestic hot water system is 44.4% more effi cient than
the baseline model.
The proposed water-cooled magnetic bearing
centrifugal chillers represent a great benefi t. Energy
modeling results presented an annual cost reduction
of 17.1% compared with the baseline. From May 2022 to
April 2023, actual energy consumption metering data
was 13.4% lower than baseline. Site energy use intensity
is currently 64.5 kBtu/ft2·yr (732.5 MJ/m2·yr) compared
to 74.4 kBtu/ft2·yr (833.9 MJ/m2·yr).
COST EFFECTIVENESS
FIGURE 1 End-use annual consumption: baseline model Standard 90.1-2010 (A) and proposed model (B).
Hot Water
5%
1,800
1,600
1,400
1,200
1,000
800
600
400
200
-9.1%
-32.4%
Hot Water
3%
-44.4%
HVAC
Lighting
Equipment
 Baseline  Proposed
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ASHRAE JOURNAL ashrae.org S E PTEM B E R 2 0 2 4
Hot Water
A cost effectiveness feasibility study was used for
purchasing the electrical chillers. Energy modeling was
performed according to these energy parameters:
 Option 1: Water-cooled electrical chiller with
magnetic-bearing centrifugal compressors from
Manufacturer X (COP = 6.19; IPLV = 10.06).
 Option 2: Water-cooled electrical chiller with
magnetic-bearing centrifugal compressors from
Manufacturer Y (COP = 6.00; IPLV = 11.08).
According to energy modeling results, Option 1
presented an annual energy cost of R$1,060,581.60,
and Option 2 of R$971,486.96. Even with a lower COP
for Option 2, this reduction was
observed and justifi ed in energy
modeling due to the great variability
of thermal load demand, which
resulted in the chillers operating-
at most-at part load part of
the time and never at full load .
Option 2, which has a higher IPLV,
demonstrated an energy cost savings
of 8.4% over Option 1. Though
Option 2's investment cost was 20%
higher than Option 1, the payback
time of this difference would be
less than two years, making it the
engineering team's choice. 
A
Equip.
23%
Lighting
31%
B
Equip.
27%
Lighting
25%
HVAC
45%
HVAC
41%
Annual Energy Consumption (MWh/Year)

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ASHRAE Journal - September 2024

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