Hello,
A colleague and I are first-time eQUEST users. We recently ran some eQUEST
simulations to analyze energy savings for lower and higher R-value
insulation scenarios for a commercial building in different climate zone
locations. The results showed decreases in natural gas use for space
heating, but there was no savings in the energy use for air conditioning. I
am trying to figure out why we did not see an energy savings for air
conditioning when wall insulation is increased.
Below is a summary of the building parameters modeled, followed by the
energy results for an R-13 insulation scenario and an (R-13 + R-4)
insulation scenario in each city. The red numbers in the results table (at
the end of this e-mail) show that increased insulation caused essentially no
change in electricity use for air conditioning, even for Miami and Phoenix,
which seems odd. Is there a problem in the way we have defined the building
air conditioning system that would cause this problem? (See info for Screens
19-25 below.) Or is there some other explanation why adding insulation would
not reduce air conditioning energy?
Thanks,
Bev Sauer
Building type
office building, 2 story
Energy code compliance analysis
none
Building Location
user-defined
cities in various climate zones evaluated
Coverage
"user-selected"
varies to generate study results - typically "all equest locations", which
allows import of specific weather data
weather file:
varies by location
Building area (ft2)
25,000
Number floor above grade
2
Cooling Equipment
DX Coils
No cooling; DX Coils; Chilled water coils; evaporative coolers
Heating Equipment
Furnace
No heating; Furnace; Electrical resistance; DX coils (heat pump); Hot water
coils
Analysis Year
user-defined - 2008
Daylighting controls
No
Usage details
Simplified schedules
SCREEN 3 Building Footprint
Footprint shape
Rectangle
Zoning pattern
Perimeter / Core
Building Orientation
north
Footprint dimensions (ft)
111.8x111.8
Perimeter zone depth (ft)
15
Floor heights
floor to floor (ft)
12
floor to ceiling (ft)
9
Pitched roof
No
SCREEN 4 Building Envelope Constructions
Roof surfaces
Construction
Metal frame, > 24 in o.c.
wood advanced frame, 24 in. o.c.; wood advanced fram, > 24 in. o.c.; wood
standard frame; metal frame, 24 in. o.c.; metal frame, >24 in. o.c.; 2 in.
concrete; 4 in. concrete; 6 in. concrete; 8 in. concrete; no exterior
exposure (adiabatic)
Exterior finish / color
Built up roof / medium (abs=0.6)
Exterior insulation
6 in. Polyisocyanurate (R-42)
several choices
Additional insulation
R-60 batt + rad barrier
several choices
Above grade walls
Construction
metal frame 2x4, 16 in. o.c.
wood frame 2x4, 16 in. o.c.; wood frame 2x4, 24 in. o.c.; wood frame 2x6, 16
in. o.c.; wood frame 2x6, 24 in. o.c.; wood frame, > 24 in. o.c.; double
standard wood frame; double advanced wood frame; metal frame 2x4, 16 in.
o.c.; metal frame 2x4, 24 in. o.c.; metal frame, 2x6, 16 in. o.c.; metal
frame, 2x6, 24 in. o.c.; metal frame, > 24 in. o. c.; 3 1/2 in. stress skin;
5 1/2 in. stress skin; 7 1/4 in. stress skin; 9 1/4 in. stress skin; 11 1/4
in. stress skin; 4 in. HW concrete; 6 in. HW concrete; 8 in. HW concrete; 10
in. HW concrete; 12 in. HW concrete; 6 in. CMU; 8 in. CMU; 12 in. CMU
Exterior finish / color
wood / plywood (abs=0.6)
aluminum; asphalt pavement (weathered); brick, CMU, concrete, film (Mylar
aluminized), glass (spandrel), marble, roofing shingle, galvanized steel
(bright), galvanized steel (weathered), stucco/gunite, vapor deposited low-e
coating, wood/plywood
Exterior insulation
user-defined
1/2 in. fiber board sheathing is default
Additional insulation
user-defined
R-13 batt
Interior insulation
user-defined
ran scenario with added R-4 sheathing
Ground Floor
Exposure
Earth contact
Construction
6-in concrete
Ext/cav insulation
no perimeter ins
Interior finish
vinyl tile
Infiltration
Perimeter (CFM/ft2)
0.038 (ext wall area)
Core (CFM/ft2)
0.001 (floor area)
SCREEN 5 Building Interior Constructions
Ceiling
Interior finish
Lay-in acoustic tile
Batt insulation
no ceiling insulation
Vertical walls
Wall type
air (none)
Floors
Interior finish
vinyl tile
Construction
6-in concrete
Concrete cap
none
Rigid insulation
none
SCREEN 6 Exterior Doors
Door type
glass
# doors on north side
1
# doors on east side
1
# doors on south side
1
# doors on west side
1
Dimensions (ft)
7x6
Construction
single clear / tint 1/4 in.
Frame type
Aluminum without brk
Frame width
3-in
SCREEN 7 Exterior Windows
Window area specification method
% gross wall area (floor to floor)
Window Type
Glass category
Double Clear/Tint
Glass type
double clear/tint 1/4 in. Air; 1) double clear; 2) double bronze
Frame type
Aluminum without brk, Fixed; width 1.30 in.
Window dimensions and positions
Window width
0
Window height (ft)
5.22
Window sill height (ft)
3
% window (flr-to-flr, including frames) on each side of building
53.3%
SCREEN 8 Exterior Window Shades and Blinds
none
SCREEN 9 Roof Skylights
none
SCREEN 13 Activity Areas Allocation
defaults
Activity areas: offices 70%, corridor10%, lobby 5%, restrooms 5%, conf room
4%, mechanical room 4%, copy room 2%. Default %s based on selected building
type.
SCREEN 14 Occupied Loads by Activity Area
defaults
Lighting, task lighting, plug loads.
SCREEN 16 Unoccupied Loads by Activity Area
defaults
SCREEN 17 Schedule Information
Occupied day
8 am - 5 pm
Other inputs
defaults
SCREEN 19 HVAC System Definitions
Cooling source
DX Coils
No cooling; DX Coils; Chilled water coils; evaporative coolers
Heating source
Furnace
No heating; Furnace; Electrical resistance; DX coils (heat pump); Hot water
coils
System type
Packaged single zone DX with furnace
Return air path
Ducted
SCREEN 20 HVAC Zones: Temperature and Airflows
Cooling setpoints - occupied (oF)
76
Cooling setpoints - unoccupied (oF)
82
Heating setpoints - occupied (oF)
70
Heating setpoints - unoccupied (oF)
64
Design temperatures
cooling indoor-75 supply-55; heating indoor-72 supply-120
Air flows
0.5
SCREEN 21 Packaged HVAC Equipment
Cooling and heating sizes
"auto"
Additional inputs
defaults
SCREEN 24 HVAC System Fans
defaults
SCREEN 25 HVAC System Fan Schedules
defaults
SCREEN 27 HVAC Zone Heating and Economizer
defaults
SCREEN 36 Domestic Water Heating Equipment
user defined
used zero in order to focus results on space conditioning
Zone 1 - Miami, FL
R-13
R-13 + R-4
ANNUAL
1000 kwh Electricity
MMBTU Natural gas
1000 kwh Electricity
MMBTU Natural gas
Space Cooling
121.33
121.34
Vent. Fans
20.16
20.04
Pumps & Aux.
0.03
0.03
Misc. Equip
92.43
92.43
Area Lights
69.16
69.16
Total (except misc & lights)
141.52
141.41
Space Heat
0.00
0.00
Zone 2 - Phoenix, AZ
R-13
R-13 + R-4
ANNUAL
1000 kwh Electricity
MMBTU Natural gas
1000 kwh Electricity
MMBTU Natural gas
Space Cooling
105.63
105.30
Vent. Fans
22.82
22.63
Pumps & Aux.
0.52
0.52
Misc. Equip
92.43
92.43
Area Lights
69.16
69.16
Total (except misc & lights)
128.97
128.45
Space Heat
1.96
1.41
Zone 3 - Charleston, SC
R-13
R-13 + R-4
ANNUAL
1000 kwh Electricity
MMBTU Natural gas
1000 kwh Electricity
MMBTU Natural gas
Space Cooling
71.41
71.71
Vent. Fans
20.22
20.10
Pumps & Aux.
0.91
0.91
Misc. Equip
92.43
92.43
Area Lights
69.16
69.16
Total (except misc & lights)
92.54
92.72
Space Heat
20.18
16.15
Zone 4 - Lexington, KY
R-13
R-13 + R-4
ANNUAL
1000 kwh Electricity
MMBTU Natural gas
1000 kwh Electricity
MMBTU Natural gas
Space Cooling
41.93
42.16
Vent. Fans
19.19
19.05
Pumps & Aux.
1.80
1.80
Misc. Equip
92.43
92.43
Area Lights
69.16
69.16
Total (except misc & lights)
62.92
63.01
Space Heat
235.60
217.67
Zone 5 - Chicago, IL
R-13
R-13 + R-4
ANNUAL
1000 kwh Electricity
MMBTU Natural gas
1000 kwh Electricity
MMBTU Natural gas
Space Cooling
35.48
35.66
Vent. Fans
19.13
19.01
Pumps & Aux.
2.24
2.24
Misc. Equip
92.43
92.43
Area Lights
69.16
69.16
Total (except misc & lights)
56.85
56.91
Space Heat
370.60
347.29
Zone 6 - Butte, MT
R-13
R-13 + R-4
ANNUAL
1000 kwh Electricity
MMBTU Natural gas
1000 kwh Electricity
MMBTU Natural gas
Space Cooling
17.43
17.67
Vent. Fans
20.07
19.95
Pumps & Aux.
2.86
2.86
Misc. Equip
92.43
92.43
Area Lights
69.16
69.16
Total (except misc & lights)
40.36
40.48
Space Heat
439.96
411.15
Zone 7 - Fargo, ND
R-13
R-13 + R-4
ANNUAL
1000 kwh Electricity
MMBTU Natural gas
1000 kwh Electricity
MMBTU Natural gas
Space Cooling
27.68
27.90
Vent. Fans
19.23
19.13
Pumps & Aux.
2.61
2.61
Misc. Equip
92.43
92.43
Area Lights
69.16
69.16
Total (except misc & lights)
49.52
49.64
Space Heat
652.86
620.95
