ASHRAE Journal - May 2024 - 57

2024 ASHRAE TECHNOLOGY AWARDS CASE STUDY
solution centers around the optimal reuse of the existing
structure to meet new spatial and performance goals
for an academic environment while minimizing carbon
expenditure (both operational and embodied).
ENERGY EFFICIENCY
A detailed energy simulation was performed using
software that complies with all the requirements in
ASHRAE Standard 90.1-2016) during the design and
planning stage of the renovation. The simulated energy
breakdown after renovation is shown in Online Figure 1,
available at https://tinyurl.com/JournalExtras.
The energy savings measures introduced in the
renovation can be summarized as follows:
z Tapping into a more efficient district chiller plant,
from a system efficiency of 1.1 kW/ton to 0.60 kW/ton
(0.31 kW/kW to 0.17 kW/kW; coefficient of performance
[COP] of 3.22 and 5.65, respectively).
z Using a hybrid ventilation system in place of
conventional air-conditioning (AC) systems.
z Using a more energy efficient air-conditioning and
mechanical ventilation (ACMV) system and controls.
z Electrostatic air cleaners used to reduce the airhandling
units' (AHUs) pressure loss while effectively
removing outdoor air particles.
z Using more energy efficient lighting and controls.
z Replacement of existing single glazing with high
performance low-e double glazing and improvement
of façade performance to balance solar protection with
daylight availability.
Based on 2022 measured data, energy consumption
was about 382,600 kWh·yr with full occupancy.
This translates to an energy use intensity (EUI) of
45 kWh/m2·yr (4.18 kWh/ft2·yr) or more than 60%
energy savings compared to energy consumption before
retrofitting.
The building performs around 20% better than its
energy simulation projection (450,000 kWh/yr), with
improvements attributable to better performance with a
hybrid system compared to simulation and optimization
of operational hours (dynamic control of spaces cooling
using a smart indoor environmental quality sensor that
tracks occupancy and space conditions).
The building is net zero, with an overall on-site
renewable energy of 464,000 kW and an overall
EUI (including renewable) of -9.5 kWh/m2·yr
(-0.88 kWh/ft2·yr).
INDOOR AIR QUALITY
Many of the AC spaces in SDE1 are designed for
hybrid cooling. As this system is a 100% outdoor fresh
air system without recirculated air (dedicated outdoor
air system), the indoor air quality is enhanced through
constant purging while simultaneously providing
sufficient cooling to achieve the temperature setpoint
of 26°C to 27°C (79°F to 81°F). By elevating internal air
velocity (using smart ceiling fans), spaces can have
higher room temperature while still achieving thermal
comfort within the predicted mean vote (PMV) of ±0.5 in
compliance with ASHRAE Standard 55-2017.
The airflow supply in each room is controlled via
variable air volume (VAV) boxes. Two proportionalintegral-derivative
(PID) loops control the room
VAV damper opening function of room dry-bulb
temperature and carbon dioxide (CO2) levels.
Smart ceiling fans are set up by default to achieve
0.7 m/s to 0.8 m/s (2.3 ft/s to 2.62 ft/s) average air
velocity at occupant desk level, but users have full
control over the speed and are allowed to adjust as
needed throughout the day.
Fresh air is supplied at the dry-bulb temperature
of 18°C-20°C (64.4°F-68°F) to maintain the room at
26°C-27°C (78.8°F-80.6°F). Average yearly indoor
humidity is about 60%-65%. The façade is also designed
to be openable (operable windows), allowing for natural
ventilation for mixed-mode hybrid cooled spaces when
there is no AC provision in the early morning or evening.
Electrostatic MERV 14 air filters are used in all preair
units and AHUs. The ozone (O3) level is regularly
measured to ensure proper operation of the units.
For spaces with a conventional AC system with
recirculation (computer and seminar rooms), CO2
sensors are installed in the room (thermostat with
built-in CO2 sensor) and in the return ducts. CO2
level setpoint is set to 750 ppm in accordance with
WELL requirements under feature A06 (Enhanced
Ventilation).
INNOVATION
A notable design feature of the new façade system
is the butterfly shades (or veil) with integrated
lightshelves. The lightshelves are positioned such that
it functions as a horizontal shading device, reducing
direct heat gain into the room while allowing natural
light to reflect and penetrate deeper into the office
MAY 2024 ashrae.org ASHRAE JOURNAL
57
https://tinyurl.com/JournalExtras http://www.ashrae.org
ASHRAE Journal - May 2024

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