Energy-Efficient Retrofit Proposal for St.Mary Church Apartments
1. St. Mary’s Church Apartments
Ruchie Kothari
Sarah Zeigler
48-752: Zero Energy Housing
Image Source: Thoughtful Balance Architects
2. Program
Mary Street Apartments is a retrofit project. The original
St. Mary’s church building is to be retrofit to
accommodate affordable housing for the elderly. The
proposed multi-residence housing facility will contain the
following facilities:
14 Apartment Units:
2 Efficiency Units ( ~ 370 sq.ft)
10 Typical units ( ~ 530 sq.ft) Typical Unit Plan
2 Accessible Units ( ~ 550 sq.ft)
Community Room
Washing + Laundry Room
Office
Rooftop Terrace
Accessible Unit Plan
3. Existing Site Conditions
Completely shaded North facade
Vaulted Ceiling, a detailing challenge! Mezzanine at the window- another
insulation detailing challenge!
Meeting Passiv Haus standards with a
rose window- has it been done before?
South Facade, excellent for solar systems
7. First Floor
Longitudinal Section Second Floor
- Thermal boundry includes first floor,second floor, new staircase and entrance lobby
- Unconditioned, insulated basement
- Area of Conditioned Space: 11577 sq.ft
- Volume of Conditioned Space: 115770 cu.ft
11. Concerns
• Moisture control
• Air tightness
• Quality (Grade) of construction when using batts for insulation
• Rockwool thermal performance
• Insufficient insulation at frame floor (thermal boundary)
• Insufficient support at ceiling for maintenance
13. Systems Overview
Components: Drawbacks:
Heating: Air to Air Heat Pumps:
Air Source to Air Heat Pumps sized for Outdoor component and indoor component; siting
2+ units is an issue with space constraints
Cooling: Air systems are less efficient than hydronic
Air Source to Air Heat Pumps size for
2+ units More ductwork in unconditioned space:
To meet IECC 2012, requires at least R-6
Back up Heat Source:
Natural Gas Furnace? No individual unit control over heating and cooling:
Who gets control? Who gets the odors?
Backup Cooling Source:
Unknown? Solar Hot Water:
80 - 120 gallons typical residential size; may be
Ventilation & IAQ: oversized for this demographic; miss out on econo-
Energy Recovery Ventilator mies of scale of a commercial system; more space
Domestic Hot Water: Heating Design Load: 114.4 kBtu/hr
Solar Hot Water System sized per unit? Cooling Design Load: 68.4 kBtu/hr
16. First Floor
Longitudinal Section Second Floor
- Thermal boundry includes first floor,second floor
- The new staircase and entrance lobby are EXCLUDED
- Unconditioned, insulated basement
- Area of Conditioned Space: 10752 sq.ft
- Volume of Conditioned Space: 107520 cu.ft
20. Frame Floor Assembly
Insulation: JM Spiderglass* + Frame Floor
Honeywell Closed cell polyurethane
foam **
Construction: 1.5”x9.5” wood studs @
16” o/c, Standard Framing
Cavity R-Value: 39.88 ft2.F.h/BTU
Framing R-Value: 9.03 ft2.F.h/BTU
Framing Factor: 13%
Overall R-Value: 33.33 ft2.F.h/BTU
Overall U-Value: 0.030BTU/h °F ft²
Rim and band joist connection
For Rim and Band Joist:
3.5” exposed closed cell spray foam
allowable at rim-joists as per Interna-
tional Residential Code (IRC)
Closed-cell spray foam better than
open-cell spray foam for moisture
control
21. Basement Assemblies
Insulation: JM Spiderglass* + Honeywell Section through Wall cavity
Closed cell polyurethane foam **
Construction: 1.5”x3.5” wood studs @ 24”
o/c, staggered wall, 2” ties
Cavity R-Value: 29.56 ft2.F.h/BTU
Framing R-Value: 6.95 ft2.F.h/BTU
Framing Factor: 9%
Overall R-Value: 27 ft2.F.h/BTU
Overall U-Value: 0.037 BTU/h °F ft²
Radon Mitigation
Use of Gravel to allow gas to flow freely under slab itself
Provide vent pipe from roof to gravel to maintain negative pressure under slab
Provide vent pipe from roof to gravel to maintain negative pressure under slab
22. Windows and Doors
Window Areas – 1361sq.ft
Window to Wall Ratio (whole building)– 0.178
Window to Floor Ratio (whole building) – 0.118
Window area per typical unit - 67.5 sq.ft.
Window orientation – Along the north and south façade. The original windows are divided
into two parts to accommodate for the second floor addition at mezzanine level. The average
window area in each typical unit is 67.5 sq.ft.
SeriousWindows 925 Series (9H pack-
age) - Casement windows have been
selected for the unit windows and pic-
ture windows have been selected for
the rose and round windows on the
north, south and east facades.
Technical Specifications
Window Type U-Value R-Value SHGC VT
Casement 0.16 6.3 0.41 0.53
Picture 0.12 8.3 0.32 0.41
Cost - ~ 60 sq.ft
Door: Main door of the building is facing east. Door selected for the church is energy star rat-
ed. manufactured by ThermaTru. The door has a u-value of 6.25hr-sq ft-°F/Btu.
25. California Loop - closed water loop system
Components:
California Loop Diagram
Heating: Units in Heating Mode
Water Source to Air Heat Pumps Units in Cooling Mode
Cooling: Expansion Tank
Water Source to Air Heat Pumps
Back up Heat Source:
Natural Gas Boiler Evaporative Condenser Boiler
50% capacity of heating design loads
Water Source Heat Pumps
Heat Sink / Backup Cooling Source:
HP HP HP
Evaporative Condenser Unit
50% capacity of cooling design loads
HP HP HP
Recapturing of Waste Heat/Cooling:
Desuperheater
HP HP HP
Ventilation & IAQ:
Energy Recovery Ventilator
26. California Loop - Precedent Case Study
Sawmill Building
Location:
Lincoln, Nebraska
Climate:
Heating dominated
Project Type:
Adaptive reuse of historical
masonry structure
Features:
Closed Hydronic System with
Water Loop Heat Pumps and
Zoned controls
Architect:
Light shelves BHV Studios,
Lincoln Nebraska
Low E, operable windoes
Images Source: WRK, LLC[19]
27. California Loop
Benefits: Drawbacks:
Economies of Scale for shared system compo- Mostly for commercial applications
nents (i.e. boiler, ERV, evaporative condenser)
Potential oversizing of equipment
High Efficiencies and Performance
Innovative & Unconventional
Hydronic Systems - 1 cubic foot of water
transfers the same amount of heat as over Requires savvy HVAC engineer
3,000 cubic feet of air [6]
Potential higher expenses
Limited amount of duct work
Requires more skilled Operations &
Smaller profile piping for hydronic systems Maintenance workers
Most system components located within
conditioned space
Individual unit control over heating and cooling
Recapture of Waste Heat and Cooling
28. Water to Air Closed Loop Heat Pumps - Sizing
Heating Design Load: 67.6 kBtu/hr
Cooling Design Load: 47.0 kBtu/hr
Proportional Heating Factor per sq.ft. = Heating Design Load / Conditioned Floor Area
Proportional Cooling Factor per sq.ft. = Cooling Design Load / Conditioned Floor Area
Heating Capacity Needed = Proportional Heating Factor x Floor Area
Cooling Capacity Needed = Proportional Cooling Factor x Floor Area
Capacity
Area Heating Capacity Cooling Capacity Pump Capacity
Zone Needed
(sq.ft.) Needed (Btuh) Needed (Btuh) (tons per unit)
(tons)
Typical Unit 530 1.06 3,249 2,259 1/2 tons
Efficiency Unit 370 0.74 2,268 1,577 1/2 tons
Accessible 560 1.12 3,432 2,386 1/2 tons
Unit
Common Area 3,592 7.18 22,016 15,307 3 tons
& Corridors
Subtotal 7,160 14.32 43,866 30,512
29. Water to Air Heat Pumps - Units
Heating Cooling
Height Width Depth Fuel
Manufacturer Model Capacity Capacity COP EER HSPF GPM Watts
(in) (in) (in) Source
(Btuh) (Btuh)
Trane GEH 006-02 9700 7500 38 51 43 4.8 12.5 16.4 1.8 600 Elec.
COP = Coefficient of Performance
ratio of energy input to energy output
higher is better
EER = Energy Efficiency Ratio
ratio of output cooling to input electrical power
11.6+ is considered high efficiency
HSPF = Heating Seasonal Performance Factor
higher is better
8+ is considered high efficiency
GPM = Gallons per Minute
Image Source: Trane [7]
30. Water to Air Heat Pump - Common Area
Heating Cooling
Height Width Depth Fuel
Manufacturer Model Capacity Capacity COP EER HSPF GPM Watts
(in) (in) (in) Source
(Btuh) (Btuh)
American Std. A1GX036 38,000 34,500 45 37 34 6.1 19.6 20.8 9.0 900 Elec.
COP = Coefficient of Performance
ratio of energy input to energy output
higher is better
EER = Energy Efficiency Ratio
ratio of output cooling to input electrical power
11.6+ is considered high efficiency
HSPF = Heating Seasonal Performance Factor
higher is better
8+ is considered high efficiency
GPM = Gallons per Minute
Image Source: American Standard [8]
31. Back-up Heating & DHW Source - Boiler
Heating Design Load: 67.6 kBtu/hr
Back up Heating: size for 1/2 of design heating load
= 33.8 kBtu/hr
Back up DHW: capacity = 18.2 kBtu/hr
Heating
Eae PE Ef Width Height Depth Fuel
Manufacturer Model Capacity AFUE
kwH/yr watts (MMBtu/yr) (in) (in) (in) Source
(MBTUH)
Natural
Bosch ZBR 16-3 52 96.1% 382 100 50.0 17.4 33.5 13.9
Gas
AFUE = Annual Fuel Utilization Efficiency
measure of thermal efficiency
higher is better
90%+ is considered high efficency
Eae = Average Annual Auxillary Electrical Energy
Consumption
lower is better
Image Source: Bosch [9]
32. Back-up Cooling & Heat Sink - Evaporative Condenser
Note: AHRI does not certify commercial
evaporative condensers nor does Energy Star
Base Heat Pump Air Flow Spray
Fan Motor Height Width Depth Fuel
Manufacturer Model Rejection Motor Rate Flow Rate
(HP) (in) (in) (in) Source
(MBtuh) (HP) (CFM) (GPM)
Baltimore Air
VC-10 147 0.5 1/3 2,900 35 79.5 47.5 36 Elec.
Coil
HP = Horsepower
unit of power
for our goals, lower is better
GPM = Gallons per Minute
measure of volumetric flow
CFM = Cubic feet per Minute
measure of volumetric flow
Has Variable Frequency Drive
Image Source: Baltimore Air Coil [10]
34. Energy Recovery Ventilator - Units
Number
Typical Unit 10
# of Persons per unit 1
Conditioned Floor Area 530 sq.ft.
CFM per person 7.5 Required Ventilation Calculation per ASHRAE 62.2-2010
CFM per floor area 5.3 7.5 CFM per person + 1 CFM per 100 sq.ft. of conditioned area
Unit Ventilation (cfm) 12.8
Total Ventilation (cfm) 128 Total Units System CFM required = 176.4 CFM
Number Total Units System Power Cosumed = 157 watts
Efficiency Unit 2
# of Persons per unit 1
Conditioned Floor Area 370 sq.ft.
CFM per person 7.5 Manufacturer Model Exhaust Air Ext. Static Ext. Static
Transfer Ratio Pressure (Pa) Pressure
CFM per floor area 3.7
(in wg)
Unit Ventilation (cfm) 11.2 Renewaire EV200 0.03@50 50 0.2
Total Ventilation (cfm) 22.4 LLC Pa/0.2inwg
Number
Accessible Unit 2 Net Air
Sensible Recovery Total Recover
# of Persons per unit 1 Flow
Efficiency Efficiency
Latent Recovery
Conditioned Floor Area 550 sq.ft. (CFM)
CFM per person 7.5 Heating 181 78 - 0.62
CFM per floor area 5.5 Cooling 180 - 52 -
Unit Ventilation (cfm) 13.0
Total Ventilation (cfm) 26.0
35. Energy Recovery Ventilator - Common Area
Number
Common Area 1
# of Persons per unit 14
Conditioned Floor Area 3,606 sq.ft.
CFM all persons 105 Required Ventilation Calculation per ASHRAE 62.2-2010
CFM per floor area 36.06 7.5 CFM per person + 1 CFM per 100 sq.ft. of conditioned area
Unit Ventilation (cfm) 141.06
Total Ventilation (cfm) 141.06 Common Area CFA = Floors 1 & 2 on same ERV unit
Total Common Area System CFM required = 141.06 CFM
Total Units System Power Cosumed = 102 watts
Manufacturer Model Exhaust Air Ext. Static Ext. Static
Transfer Ratio Pressure (Pa) Pressure
(in wg)
Renewaire EV200 0.02@50 50 0.2
LLC Pa/0.2inwg
Net Air
Sensible Recovery Total Recover
Flow Latent Recovery
Efficiency Efficiency
(CFM)
Image Source: Renewaire LLC [11] Heating 181 78 - 0.62
Cooling 180 - 52 -
37. Solar PV Array
Module Area = 12.5 square feet
Available Roof Area = 1,088 square feet on South roof facade
Number of modules = 75 modules
Total array power output = 15,000 watts or 15.0 kilowatts
38. Solar PV Generation
Assumptions:
Ideal PV array tilt:
Latitude + 15 = 55.5
Fixed Tilt
Grid-tied system
Derate Factor:
77%
Electrical Utility:
Duquesne Light
16.7 cents/kWh
Anticipated Annual
Electricity Generation:
15,500 kWh per year
39. Solar PV System Incentives [3]
Federal Incentives:
Federal Energy Renewable Tax Credit:
30% Tax Credit
State Incentives:
Pennyslvania State Solar Rebate Program:
$1.25/W DC (<=10.00kW) ($12,500.00 or 35% max)
Pennsylvania Public Utilities Commission Image Source: City of Berkeley [1]
Solar Alternative Energy Credits:
$0.40/kWh - 10 year(s)
Pennsylvania Green Energy Loan Fund
Loans of $100,000 - $2.5 million
Interest rate of 4.5% - 6%
Pennsylvania Energy Devleopment Authority Grant
up to $1 million per project
DCED - High Performancb Buildings Incentives Program
Grants: Lesser of 10% of project costs or $500,000 Image Source: energyselfreliantstates.org [2]
41. Solar Domestic Hot Water - Collection
Assumptions: Minimum Required Flat Plate Solar Collector Area = 276 sq. ft.
Panel Sizes = 4 ft. x 10 ft. = 40 sq. ft.
Ideal Solar DHW array tilt: Rougly 8 panels needed
Latitude = 40.5 Configuration = 4 columns at 4 ft. wide x 2 rows at 10 ft. high
20 ft.
Fixed Tilt
South Roof Facade 16 ft.
System Type:
Flat Plate Collector
Gallons to Area Factor:
1 gallon to 1 sq. ft.
Manufacturer:
Solvolex
Model:
Manual Glycol Horizontal Array Configuration
Image Source: solarhotusa.com [5]
42. Solar Domestic Hot Water - Storage
Assumptions: Gallons per day Solar Collector Area
Function # of Type
Required (sq.ft.)
Ideal Solar DHW array tilt: Units 14 252 252
Latitude = 40.5 Laundry 2 24 24
Subtotal - 276 276
Fixed Tilt
Tank Tank
Manufacturer Model Dia. Length
Back-up System: Capacity Materials
Natural Gas Boiler stainless
AO Smith HD36-300 300 gallons 36” 71”
steel
System Type:
Indirect Forced Circulation
Water Usage per person:
15 gallons per day
System Losses:
20%
Image Source: A.O. Smith [4]
43. Integrated Building Systems Cartoon
Equipment Location
Basement (unconditioned):
Boiler
Desuperheater
Solar DHW Water Storage Tank
Units (conditioned):
Water Source Heat Pumps
Corridor Plenum (conditioned):
Energy Recovery Ventilators
Steeple (unconditioned):
Evaporative Condenser
(replace existing wood louvers with metal louvers)
South Facade Roof (unconditioned):
Solar Photovoltaic Array
Solar Domestic Hot Water Array
South Facade Spandrel (unconditioned):
Vertical Builidng Integrated Photovoltaics
(held off of spandrel for venting)
45. Laundry Area: Clothes Washer & Dryer
Clothes Washer
Manufacturer: Ariston
Model: ARXL129+#
Fuel Type: Electricty
Capacity: 1.82 cubic feet
Energy Use: 105 kWh/year
Water Use: 3,541 gal/year
Features: Low energy & water consumption
Image Source: Ariston [17]
Clothes Dryer
Manufacturer: Bosch
Model: WTV76100US
Fuel Type: Electricty
Capacity: 3.9 cubic feet
Efficiency: 110 CFM High Air Flow
Features: Low energy & stackable
*No Energy Star Rating for Dryers
Image Source: Bosch [18]
46. Units: Range Oven & Lighting
Range Oven
Manufacturer: General Electric
Model: JAS02SNSS
Fuel Type: Electricty
Width: 24 inches
Capacity: 3.0 cubic feet
Breaker Size: 40 amps
Features: Compact; not oversized
*No Energy Star Rating for Range Ovens
Image Source: General Electric [15]
Diffused LED Lighting
Manufacturer: ZetaLux
Model: ZETA7
Fuel Type: Electricty
Watts: 7- equivalent to 50 watt incandescent
Color: cool white
Features: “Elderly report able to read under bluer light for hours
without eyestrain, compared to severe eyestrain in less
Image Source: ZetaLux [16] than 30 minutes with incandescent lighting” [11].
*Requirements don’t allow LED lighting despite higher efficiency
47. Units: Dishwasher, Refrigerator
Manufacturer: Ariston
Model: ARXL129+#
Fuel Type: Electricty
Capacity: 1.82 cubic feet
Energy Use: 105 kWh/year
Water Use: 3,541 gal/year
Features: Low energy & water consumption
Image Source: Ariston [14]
Manufacturer: SunFrost
Model: RF-12
Type: Compact
Fuel Type: Electricty
Capacity: 10.1 cubic feet
Energy Use: 171 kWh/year
Features: Low energy consumption
Image Source: SunFrost [13]
49. Benchmark Energy Balance Spreadsheet
Annual Energy Balance : convert all site energy to kWh, then use Source multipliers to do the same for Source Energy.
Site Energy (include renewable energy consumed) Source Energy
Natural gas, oil, propane, biomass, biofuel MBTUs MJ kWh MBTUs MJ
Electricity (kWh)
Heating 56,000 4,594 16,408 16,177 15,460
Cooling 12,200 1,001 3,575 3,524 3,368
Lighting & Appliances 318,300 26,113 93,262 91,951 87,871
Total Energy Consumed (kWh) 386,500 31,708 113,245 111,653 106,699
Renewable Energy MBTUs MJ kWh MBTUs MJ
Produced on site
Imported or derived from on-site processes
Purchased
Total Renewable Energy 0 0 0 0 0
Net Balance in kWh (Renewable Energy Provided-Total Energy Consumed) 113,245
Conditioned Floor Area = 11,577 sq.ft. Site EUI 33.38516023
Net Zero: NO
Comments: Assumes same appliances and lighting selection as the
proposed model; higher heating and cooling loads with
out renewable energy generation result in higher Energy
Use Intensity
50. Proposed Model Energy Balance Spreadsheet
Annual Energy Balance : convert all site energy to kWh, then use Source multipliers to do the same for Source Energy.
Site Energy (include renewable energy consumed) Source Energy
Natural gas, oil, propane, biomass, biofuel MBTUs MJ kWh MBTUs MJ kWh
Electricity (kWh)
Heating 42,900 3520 12,570 12,393 42,297
Cooling 11,600 952 3,399 3,351 11,437
Lighting & Appliances 318,300 26113 93,262 91,951 313,826
Total Energy Consumed (kWh) 372,800 30585 109,230 107,695 367,560
Renewable Energy MBTUs MJ kWh MBTUs MJ kWh
Produced on site
Solar PV Array (roof) 54,900 4,504 16,086 54,900 54,128
Solar PV Array (vertical) 100 96 343 100 1,154
Imported or derived from on-site processes
Purchased
Total Renewable Energy 55,000 4,600 16,429 55,000 55,283
Net Balance in kWh (Renewable Energy Provided-Total Energy Consumed) 92,802 312,278
CFA = 10,752 sq.ft.
Site EUI = MBTUs/sq.ft. 29.55725
Net Zero: NO
Comments: Anticipated Annual Energy Consumption from
REM Rate Model yields realistic EUI
52. Vertical Building Integrated PV Spandrel Panel
Image Source: CuttingEdgeNews [12]
Concept:
Building Integrated
Photovoltaics on Spandrel Estimated Electricity Generation
Panel on South Facade
