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Case Study - Energy Audit of UCD Student Centre 2 pg

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2 pages
Comprehensive Energy Survey of UCD Student Centre Summary UCD Building & Services Department commissioned PowerTherm to undertake a comprehensive energy survey of the one year old Student Centre. The objectives of the survey were to establish if energy consumption levels were high by comparison with similar buildings; analyse how energy was being consumed at the site; and identify cost-effective energy saving measures. The survey concluded that energy consumption levels were slightly above average; provided a detailed energy tree illustrating how energy was consumed; and identified cost-effective measures that could reduce total annual energy costs by 21%. Site Description The Student Centre consists of a 4,000 sqm building, a pedestrian walkway and a car park. Within the building are offices, meeting rooms, retail units, restaurants, a bar, a multi-purpose hall, and a central social space. Ventilation is provided by air handling units, extract fans, and openable windows. Heat for central heating and domestic hot water consumption is provided by the campus’ combined heat and power plant. Heat is delivered via radiator circuits and heating batteries in the air handling units. The operation of exterior lights, ventilation and heating systems is controlled by UCD’s Building Management System (BMS), with local operator interface. The BMS also meters heat and power consumption for the building, with submeters for the restaurant, retail units, ...
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Comprehensive Energy Survey of UCD Student Centre
Summary
UCD Building & Services Department commissioned PowerTherm to undertake a comprehensive
energy survey of the one year old Student Centre. The objectives of the survey were to establish
if energy consumption levels were high by comparison with similar buildings; analyse how energy
was being consumed at the site; and identify cost-effective energy saving measures. The survey
concluded that energy consumption levels were slightly above average; provided a detailed
energy tree illustrating how energy was consumed; and identified cost-effective measures that
could reduce total annual energy costs by 21%.
Site Description
The Student Centre consists of a 4,000 sqm building,
a pedestrian walkway and a car park. Within the
building are offices, meeting rooms, retail units,
restaurants, a bar, a multi-purpose hall, and a central
social space.
Ventilation is provided by air handling units, extract
fans, and openable windows. Heat for central heating
and domestic hot water consumption is provided by
the campus’ combined heat and power plant. Heat is
delivered via radiator circuits and heating batteries in
the air handling units. The operation of exterior lights,
ventilation and heating systems is controlled by
UCD’s Building Management System (BMS), with
local operator interface. The BMS also meters heat
and
power
consumption
for
the
building,
with
submeters for the restaurant, retail units, and bar.
Data Collection
Daily historical data was
available
from
UCD
for
building heat and power
consumption.
This
was
combined
with
daily
average
ambient
air
temperatures to evaluate
seasonal
differences,
including daily hot water
requirements.
A log was established to
automatically record meter
and submeter readings on
a 15-minute basis over a
period of 2 weeks. The
data was charted and load
changes over the course of
a day, and on different
days were assessed.
Bar Electric Load Profile
0
1
2
3
4
5
6
7
8
9
0:15
2:00
3:45
5:30
7:15
9:00
10:45
12:30
14:15
16:00
17:45
19:30
21:15
23:00
No.ofkWhper15mininterva
26-Jul-02
27-Jul-02
28-Jul-02
29-Jul-02
30-Jul-02
31-Jul-02
01-Aug-02
02-Aug-02
03-Aug-02
Seasonal Heating Loads
0
10,000
20,000
30,000
40,000
50,000
60,000
J
u
n
J
u
l
y
A
u
g
S
e
p
t
O
c
t
N
o
v
D
e
c
J
a
n
F
e
b
M
a
r
A
p
r
M
a
y
Heat Consumption (kWh)
0
50
100
150
200
250
300
350
400
Heat Cost (kWh)
Deg Days (15.5
base)
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In addition, the building design drawings, the services engineer’s calculations, and the installation
manuals were reviewed to collect information on the building size and lighting, heating pumps and
ventilation motor operating loads. The BMS provided operating load information for some of the drives
and, where necessary, an ammeter was used to verify the current drawn by some of the drives. The
BMS schedule of all lights and drives was interrogated. The building managers were questioned as to
the building occupancy period and normal operating schedule of manually controlled loads (such as
interior lights and office equipment). All this information was incorporated into a spreadsheet model to
gain an understanding of loads attributable to lighting, heating, ventilation and other equipment.
Analysis
The analysis first compared the relative energy
consumption of heat, gas and electricity.
Energy
consumption
was
then
compared
with
benchmarks for similar buildings, using Irish and UK
energy consumption data. This helped in assessing
the extent to which energy savings could be realised
from the building.
The energy tree, below, was prepared to illustrate
where energy was consumed. It helped identify the
areas
which
consumed
most
energy,
thereby
prioritising in which areas to look for energy savings.
The analysis also reflected
on the electrical load types.
For instance, it was found
that 36% of the building’s
energy consumption was due
to a low level of continuous
base load, whereas only 2%
was due to high levels during
the
short
lunchtime
peak
period.
This base load then became
the subject of further analysis
in order to establish what was
contributing to it.
Conclusions
The conclusion of the report identified 30 measures for energy saving, including housekeeping
measures, building management and monitoring measures, modifications to the BMS control, and
investments in equipment. The cost of investments were estimated, along with the likely value of the
resulting energy saving. The total value of energy savings identified amounted to 21% of the annual
energy bill (figures were adjusted down to avoid any overlap in the net effect of energy saving
measures). All measures had a paypack period of less than 4 years, with the majority of measures
having little or no cost.
The total cost of this detailed energy survey was 5.5% of the annual energy bill.
Fig. 22: Electrical Load Types
Base Load
36%
Building Opening Load
17%
Building Occupancy Load
25%
Lunchtime Peak
2%
Exterior Lights
19%
Unaccounted
1%
Annual Energy Consumed [kWh]
52%
2%
46%
Electricity
Gas
Heat