Building Performance Matters

HVAC Equipment Efficiency Overview

HVAC Components

HVAC Components: Condenser

1 Expansion valve 2 Fan 3 Compressor 4 Heat exchange coils

1 2

HVAC Components: Air Handler

1 Heat exchange coils 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 10 9 8 3 2 1 0 7 6 5 4

Source:Contracting Business Apr94, Solv ing Leakage & Return Problems

0 5 Replaced A ir = Outside

by

10 15 Percent Leak 20 25 Replaced A ir = A ttic 30

Duct Leakage

HVAC-induced infiltration

Infiltration rates 80 70 60 50 40 30 20 10 0 Florida Duct Study 1990 Fan off Fan on <0.25 0.25 0.5

0.5 0.75

0.75 1.0

1.0-1.5 1.5-2.0 >2.0

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

Closing interior doors when AHU fan on 1.2

1 0.8

0.6

0.4

0.2

0 0.16

0.42

0.62

0.94

1.15

O pe n fan off O pe n 2 cl os ed 4 cl os ed fan on A ll C lo se d

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.