Building Performance Matters
HVAC Equipment
Efficiency Overview
HVAC Components
HVAC Components: Condenser
1 Expansion
valve
2 Fan
3 Compressor
4 Heat
exchange coils
HVAC Components: Air Handler
1 Heat exchange coils
2
1
2 Fan
HVAC Components: Duct System
HVAC Components: Duct System
Supply Ducts
Supply
Plenum
Air
Handler
Return
Plenum
Return Grille
Air Conditioner Efficiencies
S easonal
E nergy
E fficiency
R atio
Minimum SEER =
10 Btu’s/Whr for central
home systems
Air Conditioner Efficiencies
SEERs range from 10 to
over 18 for very efficient
AC units.
Going from SEER 10 to
SEER 14 for example, will
reduce cooling energy
costs by about 30%.
Common Heating System Types
• Electric Strip
• Heat pump
• Gas Furnace
Common Heating System Types
• Electric Strip
• Uses either baseboard
or air handler mounted
electric resistance strips
• Low installation cost
but least efficient
option.
Common Heating System Types
• Electric Strip
• Heat pump
• Air conditioner
refrigeration cycle in
reverse (heats home
instead of cooling it).
• Cost effective vs.
electric strip in all regions
except very warm.
Common Heating System Types
• Electric Strip
• Heat pump
• Gas Furnace
• Burns natural gas or
liquid propane
• Similar efficiency to heat
pumps
Duct Leakage
Duct Leakage
Duct Leakage
Cooling System w/ Supply Leaks
Effective System EER
S y ste m E E R
10
9
8
7
6
5
4
3
2
1
0
Source:Contracting Business Apr94,
Solv ing Leakage & Return Problems
0
5
10
by
15
20
Percent Leak
Replaced Air = Outside
25
Replaced Air = Attic
30
Duct Leakage
HVAC-induced infiltration
Number of
houses
Infiltration rates
80
70
60
50
40
30
20
10
0
- Florida Duct Study 1990
Fan off
<0.25
0.250.5
0.50.75
Fan on
0.75- 1.0-1.5 1.5-2.0 >2.0
1.0
air change rate
Duct Leakage
Duct Leakage Research 1990

Florida




50 all electric homes
13% total building
leakage in duct
system
17% savings
$200 cost
Door Closure
1.2
1.15
1
0.94
0.8
0.62
0.6
0.42
0.4
0.2
0.16
fan off
fan on
ed
A
ll
C
lo
s
ed
cl
os
4
2
cl
os
ed
n
O
pe
n
0
O
pe
House air changes per hour (ach)
Closing interior doors when AHU fan on
Duct Design Problems


Utility room door that swings to the
return grill.
When the system turns on, the door is
pulled to the grill, blocking air flow.
Summary
HVAC efficiency includes:
• Selecting efficient air conditioning
based on your climate.
• Selecting the proper type of and
efficiency heating system for your
climate
• Designing and sealing air distribution
systems properly.