Air Conditioning Results Seem Strange - Help!

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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

Bev Sauer's picture
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Good morning.

Does anybody have any ideas/tips/tricks on how to model a triple-deck
multizone in Equest? Can it be done effectively?

Thanks for your help!

Adam

Adam Young's picture
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Joined: 2011-09-30
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