THE LANGUAGE OF MECHANICAL SYSTEMSAn architect’s guide to the dialects of HVAC design

Maren Longhurst, AIA, CPHC

HELLO!

Ciao! Grüezi! Gruessach mittenand!

Gruezzi wohl! Buongiorno! Hoi zame!

Gruezi Sali! Sali zamme! Hallo! Gruetzi!

Guten Tag! Hoi! Bonjour! Grüezi zäme!

Salü! Guetä Morgä! Bun di!

JARGON ?

PEAK LOADSIN WUFI

PEAK LOADSIN MANUAL J

PEAK HEAT LOAD

CALCULATION

PH = PT + PV – (PS + PI)

INDOOR DESIGN TEMP

68F to 77F

PHIUS+

70F to 75F

Manual J

OUTDOOR DESIGN TEMP

Heat Loss Equation:Q = UAΔT

SUMMER SHADING

Loads in Btuh Heating Cooling

Simplified Method:“Tight” setting 27,559 14,660

Blower Door Method:0.05 cfm50/sf env 27,551 14,637

(at 1450 sf iCFA)

INFILTRATION

ACHnat(Tight) x N factor = ACH50

ROOM BY ROOM CALC: AED

OFFICE STANDARDS

Environmental control systems tend to be treated rather like the Cinderella of architecture; given only the plainest clothes to wear, they are relegated to a back room to do the drudgery that maintains the elegant lifestyle of the other sisters: light, form, structure, and so forth.

Thermal Delight in Architecture by Lisa Heschong

MECHANICAL ROOMS

BRONZE AGE ROUND HOUSE

Image: Soluis Heritage

EQUIPMENT SELECTIONMini-split, ductless heat pump, split system

Multi-zone or multi-split system

Outdoor unit, ODU, compressor

Indoor unit, IDU, air handler, fan coil, cassette, wall mount unit, floor mount, ceiling cassette,

short-run ducted or concealed fan coil unit

Line set

Branch box

Inverter technology

MANUAL J,S,T,D

• Calculate Loads

• Size Equipment

• Calculate Air Flow

• Design Ducts

SYSTEM DESIGN

COMFORT EXPECTATIONS

ACRONYMSEfficiency = ratio of system output to system input.

Coefficient of performance (COP) = ratio of the rate of heat delivery or removal to the rate of energy input.

Energy efficiency ratio (EER) = ratio of cooling capacity in Btu/h to the rate of electric input in watts.

Seasonal energy efficiency ratio (SEER) = ratio of total cooling output during the cooling period to the total electric input.

Heating seasonal performance factor (HSPF) = ratio of total heating output of a heat pump during the heating season to total electric input.

(HSPF for heating, SEER for cooling)

EQUIPMENT SPECS

BALANCE POINT

COLD CLIMATE HEAT PUMPS

COMPATIBILITY

INSTALLED EFFICIENCY

PARTIAL LOADS

DUCT DESIGN AND AIR FLOW

PASSIVE HOUSE ZONING

S

CONTROLS

…and the Peak Cooling Load is only -16,000 BTUH!

SUGGESTED READING

Air Conditioning Contractors of Americawww.acca.org

Building Science Corporationwww.buildingscience.com

Energy Vanguard www.energyvanguard.com

Green Building Advisorwww.greenbuildingadvisor.com

PHIUS+ Certification Guidebookhttp://www.phius.org/PHIUSPlus2015docs/PHIUS+%20Certification%20Guidebook%20v1.1.pdf

Mechanical and Electrical Equipment for BuildingsWalter T. Grondzik and Alison G. Kwok

Thermal Delight in ArchitectureLisa Heschong