[Equest-users] Air Conditioning Results Seem Strange - Help!

[Bev Sauer]

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




Analysis -   eQUEST

Application Defaults 

Choices or recommendations


SCREEN 1 General Info

 

 


Project name

 

 


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

 

 

 

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