Crystal Sun
11 April 2013
ASHRAE bEQ Rating
ASHRAE Building Energy Quotient
Building Energy Quotient (bEQ) is an energy-labeling program for
commercial buildings that allows the owners identify things to target to lower
operating costs. The program measures and analyzes energy consumption, indoor
environmental quality, and the impact of costs.
The bEQ rating is primarily based off of measured site energy use intensity
(EUI) and normalized source (EUI), and ranges from 0 to 175+, where 0
corresponds to an A+ rating and is designated for buildings that have reached net
zero energy. The bEQ is calculated as follows:
𝑀𝑒𝑎𝑠𝑢𝑟𝑒𝑑 𝑠𝑖𝑡𝑒 𝐸𝑈𝐼
× 100
𝑁𝑜𝑟𝑚𝑎𝑙𝑖𝑧𝑒𝑑 𝑆𝑜𝑢𝑟𝑐𝑒 𝐸𝑈𝐼
The bEQ can be calculated based on the building “in operation,” or based on the
building “as designed.”
Building Indoor Environmental Quality (IEQ)
Another aspect of the bEQ program is indoor environmental quality, which
includes thermal comfort, lighting quality, ventilation for indoor air quality, and
overall occupancy comfort. The evaluation of thermal comfort includes visual
observation of occupant comfort (e.g. presence or absence of extra clothing, fans,
personal heaters) occupant surveys, HVAC system identification, air temperature
and relative humidity measurements. Occupants and their relative satisfaction
reported on lighting quality with the lighting on a -3/+3 scale. Indoor air quality is
evaluated based on whether the building design meets ASHRAE Standard 62.1 and
the state of air distribution systems.
Suggestions for Energy Savings
Because a main objective of the bEQ program is to identify energy savings
that are economical to the building owner, the final reports include suggestions to
improve the building envelope, lighting/daylighting, HVAC systems, and utility and
operational performance, as well as their costs and payback times.
Crystal Sun
19 April 2013
CITRIS Internship
Building Energy Efficiency Improvements
Commercial buildings are a major energy consumer in the United States, so
programs have been created to help building owners and operators identify and
implement programs and technologies to reduce energy use cost effectively. Energy
saving plans include policies, financial plans, and technical building upgrades and
retrofits. Building upgrades occur in stages to maximize financial and
environmental benefits, where each change affects the later stages.
As recommended by the EPA, the first stage of the upgrade process is
retrocommissioning. This stage provides an understanding of the overall
performance of the building and evaluates if it is operating as expected. It also
identifies equipment that needs to be replaced or other operational issues that
should be addressed to improve building performance. In Sutardja Dai Hall (SDH),
the HVAC systems were commissioned in 2009, but the building owner has not yet
received a report. Currently, building heating is provided by the campus steam loop
(byproduct of campus cogen), and cooling is provided by electric centrifugal chiller
in the winter, steam absorption chiller in the summer. To date, there are no
renewable energy sources on site. To improve energy efficiency, the building is
undergoing a monitoring-based commissioning project (MBCx).
The next stage includes upgrades in lighting systems, since lighting affects
other aspects of building performance. In SDH, direct-indirect luminaries provide
open office area lighting with EMS-based scheduling for open areas, while private
offices also have installed occupancy sensors. Ceiling lamps are fluorescent T8
lamps with 3500K color temperature. Some suggestions posed by the recent bEQ
review were to de-lamp light fixtures in open office areas and install LED task
lighting with occupancy sensors, reduce the number of lamps in hallways from 2
lamps to 1 lamp per fixture, daylight controllers that dim during daytime, and
replace stairwell lighting with occupancy sensing fixtures.
In terms of air handling, SDH has two variable air volume (VAV) air handlers
with zone reheat. The handlers control the outside air intake using a modulating
economizer with minimum outside air damper. These airhandlers consume about
39% of the building’s total energy use. Through the MBCx project, the building’s
HVAC system will be improved by installing variable frequency drives on water
pumps. In addition, the air-handling units were recommended to be installed with
high-capacity filters on all units.
As a whole, the building has detailed sub-metering that allows for accurate
disaggregation of space type and end use of energy. This is especially useful because
the building contains several different uses: offices, nanofabrication lab, and a
dining center.
Crystal Sun
26 April 2013
CITRIS Internship
Sutardja Dai Hall Building Power
Each plug and lighting fixture in Sutardja Dai Hall (SDH) has associated
power demand, power factor, and reactive power trends that vary throughout the
day. The demand is simply the power consumed by each load in kW. The power
factor is a value that ranges from -1 to 1 that is defined as the ratio of the real power
flowing into the load and the apparent power in the circuit. Apparent power is the
sum of real power and reactive power, where reactive power is power that is not do
work at the load, but generates waste heat in the wires.
In general, demand (kW) for each load remains constant between 8 PM and 6
AM the following morning. Each load carries between 5-30 kW during peak hours 6
AM to 8 PM. There are some loads (EOMD) that are consuming over 145 kW at any
given moment, so operational inspections and efficiency checks on these loads may
lead to additional energy savings. On a building scale, SDH is using over 1000 kW at
peak hours (2 PM – 6 PM), as measured by building submeters.
Crystal Sun
26 April 2013
CITRIS Internship
Sutardja Dai Hall Building Power
Each plug and lighting fixture in Sutardja Dai Hall (SDH) has associated
power demand, power factor, and reactive power trends that vary throughout the
day. The demand is simply the power consumed by each load in kW. The power
factor is a value that ranges from -1 to 1 that is defined as the ratio of the real power
flowing into the load and the apparent power in the circuit. Apparent power is the
sum of real power and reactive power, where reactive power is power that is not do
work at the load, but generates waste heat in the wires.
In general, demand (kW) for each load remains constant between 8 PM and 6
AM the following morning. Each load carries between 5-30 kW during peak hours 6
AM to 8 PM. There are some loads (EOMD) that are consuming over 145 kW at any
given moment, so operational inspections and efficiency checks on these loads may
lead to additional energy savings. On a building scale, SDH is using over 1000 kW at
peak hours (2 PM – 6 PM), as measured by building submeters. It is useful to note
that SDH has humongous chillers that are not efficient at current capacity.
Definitions:
Deadband: Most generally, a deadband is a range in which a system has no activity.
In terms of building HVAC systems, the deadband allows temperature to drift
between temperatures without activating heating or cooling. Expanding the
deadband range can be thought of as dulling the sensitivity of the system to
temperature fluctuation to save energy.
Load factor: Defined as the average load divided by the peak load. It is a measure of
how flat an energy curve is, that is the constancy of energy use. High load factors
mean that energy use is constant, while low load factor shows that there is
variability in energy use. Electricity rates are set so that high load factor customers
pay less per kWh, which helps reduce peak energy use (peak shaving).
Types of HVAC systems
Variable Air Volume: In simple VAV systems, air supply temperature is constant, so
airflow rate must be adjusted to account for the desired temperature changes. This
means more control over fans, and airflow in multiple zones can be varied as well.
Constant Air Volume: In CAV systems, supply air flow rate is constant, but
temperature is adjusted to meet the needs of the space. CAV systems in larger
buildings is rare because they typically serve smaller zones and do not offer any
energy benefits on a larger scale.