Multifamily Housing Retrofit: 1109 Liverpool

MANCHESTER, PA 1109 LIVERPOOL ST.

Xiaopeng Ma /xiaopenm@andrew.cmu.edu/ Duy Vo /dvo@andrew.cmu.edu/

TABLE OF CONTENT SITE CONTEXT BUILDING INFORMATION

4 5

A. General Information

5

B. Thermal Boundary

6

PROJECT SCOPE OF WORK BASELINE MODEL

7 8

A. Existing Floor Plans

9

B. Baseline Enclosure System

9

C. Baseline Mechanical System

13

D. Lighting & Appliances

13

E. Infiltration & Air Leakage

15

F. Baseline Energy Balance Spreadsheet

15

URA COMPLIANT MODEL

16

A. URA Compliant Framed Wall Assembly

17

B. Exhaust Only Ventilation

18

C. URA Compliant Energy Balance Spreadsheet

19

BASELINE MODEL

20

A. Building Shape

21

B. Baseline Enclosure System

22

C. Energy Recovery Ventilation System

25

D. Infiltration & Air Leakage

26

E. HVAC System

26

F. Solar Thermal

28

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TABLE OF CONTENT G. Photovoltaic Panels

29

H. Integrated Mechanical System

30

I. Proposed Design Energy Balance Spreadsheet

31

ENERGY PERFORMANCE ANALYSIS CONCLUSION APPENDIX List of Assumptions Used

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LIST OF FIGURES & TABLES List of Figures Figure 1 . Building Site Indicator Map Figure 2. View of the Northern facade Figure 3.. View of the Southern facade Figure 4. Panoramic view of the building and its surrounding context Figure 5. Building Overall Thermal Boundary Figure 6. Project Scope of Work Diagram Figure 7. Rendering of the baseline model in its context Figure 8. Floor plans for the retrofit proposal done by Robert Baumbach Design Figure 9. Overall section of the baseline model Figure 10. Baseline framed floor assembly detail Figure 11. Baseline framed wall assembly detail Figure 12. Baseline framed roof assembly detail Figure 13.. Baseline double-glazed window Figure 14. Rendering of the URA compliant model in its context Figure 15. URA compliant framed wall assembly detail Figure 16. Air King Exhaust Fan Figure 17. Apollo Exhaust Fan Figure 18. Rendering of the proposed design model in its context Figure 19. Proposed 2nd floor plan Figure 20. Proposed 3rd floor plan Figure 21. Overall section of the proposed design model Figure 22. Proposed framed floor assembly detail Figure 23. Proposed framed wall assembly detail Figure 24. Proposed framed roof assembly detail Figure 25.. Proposed triple-glazed window Figure. 26. Renewaire BR7O ERV Figure 27. Ground Source Heat Pump (GSHP) operational diagram Figure 28. Solar Thermal operational diagram Figure 29.. Rendering of both PV array and Solar Thermal system Figure 30. Integrated mechanical system diagram Figure. 31.. Baseline percentage of end use Figure..32. Proposed design percentage of end use Figure. 33 Cumulative annual energy consumption of individual upgrade strategy Figure 34. Energy saving of individual upgrade strategy Figure. 35. Cumulative energy cost saving of individual upgrade strategies Figure 36. Energy cost saving of individual upgrade strategies

List of Tables Table 1. Baseline HVAC system details Table 2. Baseline Model Energy Balance Spreadsheet Table 3. Exhaust fan details Table 4. URA Compliant Model Energy Balance Spreadsheet Table 5. ERV Specifications.

Table 6. Heating and Cooling design loads Table 7. Air Source Heat Pump (ASHP) specifications Table 8. Air Source Heat Pump (ASHP) effectiveness analysis Table. 9. Ground Source Heat Pump (GSHP) specifications Table 10. Solar Thermal system specifications Table 11. Photovoltaic (PV) roof panel specifications Table 12. Proposed Design Energy Balance Spreadsheet Table 13. Effectiveness of individual upgrade strategies

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ยงSITE CONTEXT

The building investigated in this study is located at 1109 Liverpool street, Manchester, PA. Manchester is a borough of Allegheny County, and is approximately 10-minute-drive from Pittsburgh. Manchester has a total population of 2,763 people with a total area of 0.8 square miles. It has a heating dominated climate similarly to that of Pittsburgh with 726 cooling degree days and 5829 heating degree days. Prior to the completion of the project, we visited the site, and from our observations, we concluded that the area in which the building is located is predominantly residential with quite a few unoccupied, dilapidated buildings and vacant lots.

Figure 1 . Building Site Indicator Map

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BUILDING INFORMATION A. General Information

Figure 2. View of the Northern facade

Figure 3.. View of the Southern facade

The building at 1109 Liverpool street is part of the Manchester Historic effort, therefore facade preservation efforts are highly emphasized. The building does not have a true North-South orientation, but rather it is slightly tilted towards the Northwest direction. It currently unoccupied with all windows and doors boarded up. There are several other unoccupied buildings and an empty lot located adjacent to it.

The building is a multifamily housing building with 3 different floors. The retrofit proposal for this building

by Robert Baumbach Design allocates 2 residential units on the 2nd and 3rd floor of the building, while the bottom floor is designated for commercial use. The building has a basement, whose purpose is not clearly indicated. We suspected that perhaps it was used strictly for storage. The South side of the building has a firescape and is adjacent to an open lot.

Figure 4. Panoramic view of the building and its surrounding context

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B. Thermal Boundary

This building is a mixed use multifamily building with 2 residential units on top of a retail unit. There are 2 bedrooms in each residential units accommodating for 2 occupants. As previously mentioned, the use of the basement was not clearly indicated in the drawings provided by Robert Baumbach design. With that said, we made an assumption that the basement would be used strictly for storage, thus it would neither have any mechanical equipment nor would it be conditioned. Consequently, the overall thermal boundary for the building only occurs from the retail floor to the 3rd floor. The total conditioned area was determined to be 4,773 sq.ft, while the volume of conditioned area equated to 50,899 cu.ft.

Figure 5. Building Overall Thermal Boundary

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PROJECT SCOPE OF WORK We were tasked to explore various possibilities in regards to upgrading the building. Our approach was to create 3 different models, namely baseline model, URA compliant model and proposed design model using REMRATE. • Baseline model: Robert Baumbach Design came up with a retrofit proposal for this particular building and provided us with their set of drawings. We created a baseline model based on their proposal and some of our own assumptions. The main goal for this model was to see whether RBD’s proposal had met the URA guideline as well as the Energy Star Version 3.0 • URA compliant model: After assessing the baseline model, we realized that it did not meet the URA guideline as well as the Energy Star Version 3.0. We then created a URA compliant model mainly to see what it would take to meet these guidelines.

• Proposed design model: After having gain an understanding of the two aforementioned models, we proceeded to create a model that rigorously pursued net-zero goal. Cost estimating was not included in our selection of strategies, however the results from the energy performance analysis for this model provided insights into the effectiveness of each strategy.

Baseline Model (Created using the information provided by Robert Baumbach Building Design as well as some of our own assumptions)

SCOPE OF WORK

URA COMPLIANT Model Baseline model adjusted to meet URA design guideline

PROPOSED DESIGN Model Model created to both meet URA guideline and net to zero Figure 6. Project Scope of Work Diagram

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BASELINE MODEL

Figure 7. Rendering of the baseline model in its context

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A. Existing Floor Plans

These floor plans (figure.) below were provided as part of the retrofit proposal done by Robert Baumbach Design. In general, the layout of the 2 residential units is relatively simple with the living room placed on the North side of the building and master bedroom placed on the South side of the building.

Currently, there are 2 porches located on the West side of the building that look to the side of the adjacent building.

Figure 8. Floor plans for the retrofit proposal done by Robert Baumbach Design

B. Baseline Enclosure System

In order to create the REMRATE model, we first investigated and tried to gain understanding of the construction of the shell of this building. As previously mentioned, we were provided with a set of drawings by the architect, from which we were able to extract information. However, we did not gather a sufficient amount of information on the enclosure, thus we had to make several assumptions in order to help us complete the REMRATE model. Below are the following assemblies that we investigated and modeled: • Framed Floor Assembly • Framed Wall Assembly • Framed Roof Assembly • Glazing Type

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Figure 9. Overall section of the baseline model

a. Baseline framed floor assembly

It was indicated in the drawing sets provided by the architect that the framed floor, which is composed of 2x10 joists, has the 2-hour fire rating. From the drawings, we know that the current assembly has a 3/4 inch wood flooring layer laid on top of 3/8 inch plywood sheathing that sits above the framed floor. There was no indication on whether the insulation was present in between the floor joists. However, since we decided that the basement would not be conditioned, it was necessary for us to introduce 10 inch of fiberglass batt insulation in between the 2x10 floor joists. After modeling the assembly in REMRATE, a R-value of 30 was achieved.

b. Baseline framed wall assembly

It was indicated in the drawing sets that there would be replacement of furred out wall with newly insulated 2x4 stud wall to solve mold growth issues. Based on that piece of information and the drawings, we made the assumption that the existing wall would be composed of both brick masonry layer and a 2x4 stud wall layer. The insulation used in the stud wall, as specified by the architect, is 4in. fiberglass batt. This amount of insulation would be installed in between the studs. An R-value of 10 was resulted.

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1/2 in. gypsum

4 in. fiberglass batt insulation 5/8 in. plywood sheathing 3/4 in. wood flooring 5/8 in. plywood sheathing 10 in. fiberglass batt 2x10 floor joists Figure 10. Baseline framed floor assembly detail

4in. framed wall stud 5/8 in. plywood sheathing 4 in. fiberglass batt insulation 1/2 in. gypsum

Figure 11. Baseline framed wall assembly detail

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c. Baseline framed roof assembly

Similarly to the floor assembly, the roof assembly, as specified by the architect, has the 2-hour fire rating. In addition, the roof insulation was indicated to be R-38 multi layer polyiso rigid insulation, which we determined the thickness to be roughly 7.5 inches. This rigid insulation sits on top of the 3/4 in. plywood sheathing and 2x10 framed roof. The architect also specified a layer of black EPDM rubber roofing to be installed for the roof surface. The R-value was determined to be 38.

EPDM rubber roofing

3/4 plywood sheathing

7.5 in. rigid insulation 2x10 roof joists 3/4 plywood sheathing

Figure 12.. Baseline framed roof assembly detail

d. Baseline glazing type Because of the preservation efforts, the windows were to be custom made by Allied Mill of Pittsburgh in order to keep their historical aesthetic. The glazing type was specified by the architect to be double-glazed, moderate solar gain low-e glass with argon filled.

Window Properties

Values

U-value SHGC Tvis

0.3 0.32 0.5

Multifamily Housing Retrofitting: 1109 Liverpool, Manchester PA

Figure 13.. Baseline double-glazed window

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C. Baseline Mechanical System For the baseline mechanical systems, both heating and cooling equipment is selected based on the requirement in the design document that is provided. Each floor will be provided with a gas furnace and an air conditioner to provide both heating and cooling. As to the domestic hot water system, a 75 gallon gas fired hot water tank is proposed, which, according the average hot water consumption of residential buildings, should be sufficient to provide hot water for all three floors. Although the basement is not conditioned and insulated, the hot water storage tank and the pipes can be insulated to avoid heat loss. Detailed information of those systems is provided in the figure below.

Baseline HVAC system (All systems meet the requirement of Energy Star Version 3)

System Heating

Cooling

Domestic Hot Water (DHW)

Type 92 AFUE Gas Furnace 13 SEER Air Conditioner 13 SEER Air Conditioner 0.68EF Gas Boiler

Capacity

Served Space No. of Units

3 ton

1 for Each Floor

3

3 ton

1st Retail Floor

1

2 ton

2nd & 3rd Floors

2

75 Gal

All Building

1

Table 1. Baseline HVAC system details

D. Lighting & Appliances

No detailed information about lighting is provided in the design document. According to IEEC 2012, 75% of the light should be high-efficient. Therefore, aiming at being energy efficient and meeting the rigorous requirement, it is assuming that 80% of the lighting will be Compact Fluorescent Lights (CFLs).

As to appliances, the design document specified the total spending allowance to be $3,500/unit.

In addition, URA guideline requires all the appliances to be Energy Star qualified. Therefore, Energy Star qualified products are selected while the total cost of them is controlled below $3,500/unit.

Harbor Breeze 56-in Brushed Nickel Ceiling Fan ENERGY STAR Cost: $99.98 Airflow Efficiency: 102 CFM/Watt

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Whirlpool 24-in Built-In Dishwasher (Black) ENERGY STAR Cost: $329 Energy Consumption: 282 kWh/yr

Whirlpool Gold 30-in 2.1 cu ft/3.9 cu.ft Double Oven Gas Range Cost: $1349

Samsung 3.6 cu.ft Large Capacity Front Load Washer Cost: $846 Washer LER: 94 kWh/yr

Roper 6.5 cu ft Gas Dryer (White) Cost: $499 Efficiency Factor: 2.67

Multifamily Housing Retrofitting: 1109 Liverpool, Manchester PA

Frigidaire 14.8 cu. ft.

(Top Freezer Refrigerator) Cost: $499 Energy Consumption: 355kWh/yr

We’ve made the assumption that 80% of the building’s light bulbs are CFLs

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E. Duct Leakage & Infiltration

Both duct leakage and infiltration rate are not mentioned I the design document. However, in order to meet the requirement of URA guideline, certain level of duct leakage and infiltration is required. Therefore, it is assumed that the building will meet the minimum requirement after retrofits. Detailed requirements are as follow: Duct leakage: • Total duct leakage =8 CFM25 per 100 sq. ft • Duct leakage to outdoors =4 CFM25 per 100 sq. ft.

Infiltration: • 4 ACH50.

F. Baseline Energy Balance Spreadsheet

As revealed in the energy balance spreadsheet, the final Site EUI is 46.4 MBTU/sf, while the source EUI is 77.9 MBTU/sf. Comparing with the average U.S. average EUI of single family building, which is 44 MBTU/sf, this building is slightly higher than the average level.

Site Energy (include renewable energy consumed)

Source Energy

Natural gas, oil, propane, biomass, biofuel

MBTUs

MJ

kWh

MBTUs

MJ

kWh

Water Heating

36,300

37,985

10,636

39,640

41,480

11,614

Space Heating

128,100

134,048

37,533

139,885

146,380

40,986

Lighting & Appliances

52,900

55,356

15,500

178,009

186,273

52,156

Cooling

4,200

4,395

1,231

14,133

14,789

4,141

Total Energy Consumed (kWh)

221,500

231,784

64,900

371,666

388,922

108,898

Renewable Energy

MBTUs

MJ

kWh

MBTUs

MJ

kWh

Produced on site

0

0

0

0

0

0

0

0

0

0

0

0

Electricity (kWh)

kWh

Imported or derived from on-site processes Purchased Total Renewable Energy Net Balance in kWh (Renewable Energy Provided-Total Energy Consumed)

64,900

US Residential Avg EUI: 44 MBTU/ft2

Site EUI (MBTU/sf)

46.4

108,898 Source EUI (MBTU/sf)

77.9

Table 2. Baseline Model Energy Balance Spreadsheet

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URA COMPLIANT MODEL

Figure 14. Rendering of the URA compliant model in its context

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After having conducted the energy performance analysis of the baseline model, we realized that the retrofit design proposed by the architect did not meet the URA guideline and the Energy Star Requirement Version 3.0. We viewed the report generated directly from REMRATE and identified the 2 main reasons for why that occured. They are as follow: • The framed wall assembly does not have sufficient thermal performance • Initially we assumed that due to the age of the building, mechanical ventilation was not present in the original design of the building. Instead, we assumed that natural ventilation was employed.

After having identified the limitations of the retrofit proposal, we created a URA compliant model in order to figure out what it would take to meet the URA guideline and Energy Star Requirement Version 3.0.

A. URA compliant framed wall assembly

For the URA compliant model, we decided to space the 2x4 stud wall 2 inches away from the existing

brick wall. By doing that, we allowed for space to directly apply 2 inches of spray polyurethane insulation foam onto the brick. There are 2 benefits to the application of the spray foam: • Because spray polyurethane spray foam is a vapor retarder, a 2 in. thick of this insulation would prevent any moisture-related issues that may occur within the wall assembly.

• Additionally, the spray polyurethane foam, with a R-value of 5.6 per inch, would increase the overall thermal performance of the wall assembly.

4in. framed wall stud 2 in. spray polyurethane insulation applied directly onto the brick wall 4 in. fiberglass batt insulation inserted between 2x4 studs 1/2 in. gypsum Existing brick masonry wall

Figure 15. URA compliant framed wall assembly detail

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B. Exhaust Only Ventilation

For the URA compliant model, we decided to employ the exhaust only ventilation system. This system is most commonly found approach in most residential buildings across the U.S. We assumed that the exhaust fans would only be installed in the bathrooms of the 3 units and that the operation hours are 12 hours per day. One thing to note here is that this ventilation system, though commonly used, is especially problematic in the region of Pittsburgh where radon risk is high. As the building becomes tighter, exhaust only approach creates negative pressure within the building which then draws the radon up to where the occupants live.

For second floor and third floor, the flow rate requirement is 60cfm. For retail floor it is 30 cfm.

Figure 16. Air King Exhaust Fan

Brand

Air King

Apollo

Model Name

BFQ50

QB89BC

Number of Speeds

1

1

As-Tested Airflow (cfm)

50

60

Fan Efficacy (cfm/W)

1.8

2.0

Hours/day

12

12

Fan Watts

90

120

Area Served

1st Floor

2nd & 3rd Floors

Table 3. Exhaust fan details

Figure 17. Apollo Exhaust Fan

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C. URA Compliant Model Energy Balance Spreadsheet

As revealed in the energy balance spreadsheet, the final Site EUI is 41 MBTU/sf, while the source EUI is 75 MBTU/sf. Comparing with the average U.S. average EUI of single family building, which is 44 MBTU/ sf, this URA compliant building is slightly lower than the average level. We saw a decrease in space heating load due to better thermal performance of the wall. However, space cooling load increased. As the thermal performance becomes better, heat loss becomes less likely which means that internal heat gain in the summer would remain inside the building. Consequently, this drives the cooling load up. In addition, there was an increase in lighting & appliances. This is due to the introduction of exhaust fans.

Site Energy (include renewable energy consumed)

Source Energy

Natural gas, oil, propane, biomass, biofuel

MBTUs

MJ

kWh

MBTUs

MJ

kWh

Water Heating

36,300

37,985

10,636

39,640

41,480

11,614

Space Heating

98,600

103,178

28,890

107,671

112,670

31,548

194,834

203,879

57,086

Electricity (kWh)

kWh

Lighting & Appliances

57,900

60,588

16,965

Cooling

4,700

4,918

1,377

15,816

16,550

4,634

Total Energy Consumed (kWh)

197,500

206,670

57,868

357,960

374,579

104,882

Renewable Energy

MBTUs

MJ

kWh

MBTUs

MJ

kWh

Produced on site

0

0

0

0

0

0

0

0

0

0

0

0

Imported or derived from on-site processes Purchased Total Renewable Energy Net Balance in kWh (Renewable Energy Provided-Total Energy Consumed) US Residential Avg EUI: 44 MBTU/ft2

57,868 Site EUI (MBTU/sf)

41

104,882 Source EUI (MBTU/sf)

75

Table 4. URA Compliant Model Energy Balance Spreadsheet

Multifamily Housing Retrofitting: 1109 Liverpool, Manchester PA

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PROPOSED DESIGN MODEL

Figure 18. Rendering of the proposed design model in its context

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After having understood the energy performance of the baseline model as well as what it would take to meet the URA guideline and Energy Star Version 3.0, we proceeded to create a model that strove to net out to zero. We proposed a series of upgrade strategies and conducted analysis on the effectiveness of each strategy. We left lighting and appliances similar to what we used in the baseline model since they already meet Energy Star requirements. Below are the proposed strategies: • Building Shape • Proposed enclosure system • Infiltration & Duct Leakage • Energy recovery ventilation system • Ground Source Heat Pump • PV Panels & Solar Hot Water

A. Building Shape

2nd Bedroom

WC

1st Bedroom Living room connected to dining room and kitchen

Figure 19. Proposed 2nd floor plan

2nd Bedroom

WC

1st Bedroom Living room connected to dining room and kitchen

Figure 20. Proposed 3rd floor plan

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As previously mentioned, the 2 residential units each have a porch that looks into the side of the adjacent building. For the proposed design model, we decided to remove those 2 porches. By doing that we were able to achieve the following: We were able to enlarge the bedrooms, allowing for more closet space within the units We were able to dedicate more space to the mechanical closet. It is typical that mechanical system would be squeezed in a closet, which is difficult for maintenance/repair person to properly prepare the system should problems occur. By giving more space to the mechanical closet, it should allow for ease in repair and maintenance of mechanical system.

B. Baseline Enclosure System Below are the following assemblies that we investigated and modeled: • Framed Floor Assembly • Framed Wall Assembly • Framed Roof Assembly • Glazing Type

Figure 21. Overall section of the proposed design model

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a. Proposed framed floor assembly

For the proposed framed floor assembly, we replaced 10 inches of fiberglass batt insulation with 6 inches of spray icynene insulation in between the 2x10 floor joists. We also insulated around the band joists with icynene in order to reduce unwanted heat loss from the perimeter of the framed floor. By strategically adding icynene, a much better insulation material (R6.5/inch) than fiberglass batt (R3.1/inch), it not only increases the thermal performance of the framed floor but also prevents any moisture related issues from occurring. The resulting R-value of the floor turned out to be 40. The detailed assembly can be seen in figure 22.

b. Proposed framed wall assembly

For the proposed framed wall assembly, we decided to keep the same approach as the URA compliant model, which is to space the 2x4 stud wall away from the brick allowing for direct application of spray foam.

This method eliminates thermal bridging due to framing factor while preventing moisture-related issues from occurring within the assembly. Differently from the URA compliant model, for this particular model, we decided to employ only icynene for the insulation. We replaced the 4 inches of fiberglass batt insulation between the studs with 4 inches of spray icynene. By doing this, we were able to increase the thermal performance of the wall to R-40. However, it is important to note that this strategy is much more expensive than the hybrid approach presented in the URA compliant model. The detailed assembly can be seen in figure 23.

6 in. icynene applied in between the floor joists & around the band joists 3/4 in. wood flooring

5/8 in. plywood sheathing

2x10 floor joists

Figure 22. Proposed framed floor assembly detail

Multifamily Housing Retrofitting: 1109 Liverpool, Manchester PA

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Existing brick wall

2X4 sill plate 1/2 in. gypsum 4 in. icynene applied in between the 2x4 studs 2 in. icynene applied directly onto the brick wall Figure 23. Proposed framed wall assembly detail

White EPDM roofing 3/4 plywood sheathing

7.5 in. rigid insulation

4 in. blown icynene 3/4 plywood sheathing 2x10 roof joists

Figure 24. Proposed framed roof assembly detail

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c. Proposed framed roof assembly

For the proposed framed roof, we decided to add 4 inches of blown insulation in between the 2x10 roof joists. By doing this, we were able to increase the total R-value of the roof assembly 60. One thing to note here is that we decided not to fill up the 10 inch stud cavity of the roof, mainly because we wanted to leave 6 inches open to run the ducts through. In addition to the insulation, we also replaced the black EPDM rubber roofing with a white EPDM roofing. There were several reasons for why we did this.

• By using light color roofing material, we would be able to reflect sunlight, thus cool the roof down.

• Because the roof would be much cooler, we then would be able to reduce the urban heat island effect while maintaining the efficiency of the PV array and SHW system.

d. Proposed glazing type We still adhered to the preservation guideline of the Manchester Historic District in regards to the overall aesthetics of the windows.

However for the proposed glazing type we upgraded it to tripleglazed, moderate solar gain low-e glass with argon filled from the double-glazed type previously proposed in the baseline

Window Properties

Values

U-value

0.22

SHGC

0.26

Tvis

0.45

Figure 25.. Proposed triple-glazed window

C. Energy Recovery Ventilation System • For the reasons mentioned in former section, exhaust-only mechanical ventilation system is not feasible in houses with high airtightness. According to ??, for buildings with ACH50 of less than 3.5, it is necessary to have both supply and exhaust ventilation system to provide sufficient fresh air. Therefore, balanced ventilation system equipped with Energy Recovery Ventilator (ERV) is proposed. The principle of the ERV is to transport fresh air and exhaust air through a heat exchanger where part of both sensible and latent heat in the exhaust air can be transferred to the fresh air, therefore preheating or precooling the air and saving energy.

• Each floor will be equipped with an Energy Recovery Ventilator that is sized based on the fresh air requirement. Figure X and Table X have revealed detailed information of the ERV selected

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For second floor and third floor, the flow rate requirement is 60cfm. For retail floor it is 30 cfm.

Renewaire BR70 ERV Sensible Recovery Efficiency

0.3

Total Recovery Efficiency

0.32

Flow Rate (cfm)

0.5

Hours per day

9

Fan Watts

94

Figure. 26. Renewaire BR7O ERV

Table 5. ERV Specifications.

D. Infiltration & Duct Leakage Infiltration and duct leakage is a primary factor of energy loss. In order to further improve the energy performance of the building, it is assumed that more rigorous requirement of duct sealing and infiltration control that is required in IECC 2012 is met. Detailed information is indicated below Duct leakage: • Total duct leakage =4 CFM25 per 100 sq. ft • Duct leakage to outdoors =2 CFM25 per 100 sq. ft.

Infiltration • 2.5 ACH50.

E. HVAC systems To improve the heating and cooling system, both air source heat pump and ground source heat pump are investigated. Since there are three units in this multifamily building where the first floor serves as retail space and the upper two floors serves as residential apartment, it is decided to use separated HVAC system for each floor. Therefore, each of the units is modeled to predict the heating and cooling design load, in order to size the HVAC system. The loads are illustrated in Table X. As revealed, the third floor has the largest heating and cooling load, since it has the most exposed surfaces.

Multifamily Housing Retrofitting: 1109 Liverpool, Manchester PA

Heating Design Load (kBTU/yr)

Cooling Design load (kBTU/yr)

1st floor

11.2

6.5

2nd floor

11.5

7.7

3rd floor

13.3

8.8

Total Area

36

23

Table 6. Heating and Cooling design loads

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a. Air Source Heat Pump

Air source heat pump is sized for each floor based on their respective design loads, which is illustrated in Table Y. Products are AHRI certified and their efficiency has met the requirement of Energy Star Version 3 for climate zone 5, which is equal or larger than HSPF of 9.25, SEER of 14.5, or EER of 12 with electric backup.

Heating Design load (kBTU/yr) 1st floor 11.2 2nd floor 11.5 3rd floor 13.3

Cooling Design load (kBTU/yr) 6.5 7.7 8.8

ASHP Heating load 12.6 12.6 13.6

ASHP Cooling load 11.9 11.9 12

ASHP Heating efficiency (HSPF) 10 10 9.25

ASHP Cooling efficiency (SEER) 20 20 17.8

Table 7. Air Source Heat Pump (ASHP) specifications

As revealed in Table Z, although the total energy consumption decreases by 18.7%, the annual energy cost increases by 8.2% and the HERS index also increases by 2.1%. The reason for it should be that the ASHP uses electricity for heating, which could save energy when compared with the base case system that uses natural gas. However, the high price of electricity has increased the energy cost. In addition, one of the reason that air source heat pump may not work very well in this climate is that the winter is harsh and there is little heat that can be drawn from the outside air.

Total Annual Energy Consumption (MMBTU) Annual Energy Cost ($) HERS Score

Base HVAC system

ASHP

Reduction

% Reduction

144.6

117.6

27

18.7%

3405 48

3684 49

-279 -1

-8.2% -2.1%

Table 8. Air Source Heat Pump (ASHP) effectiveness analysis

a. Ground Source Heat Pump

Ground source heat pump is also investigated as an alternative system. It is sized based on the total heating and cooling loads. An AHRI certified 3 ton water loop ground source heat pump is chosen for this multifamily building. The ground water loop will then directly exchange heat with the heat pump in each floor. Detailed specification of it is illustrated in Table X. To provide sufficient heating or cooling to the 3 ton ground source heat pump system, three 150 feet deep vertical wells are needed. The three wells need to be placed 15 to 25 feet apart. Considering the size of the backyard, there is abundant space to locate the wells.

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3 ton AQUARIUS WW036-3 GSHP Heating Capacity (Kbtu/hr)

37

Heating Efficiency (COP)

4.4

Cooling Capacity (Kbtu/hr)

25.5

Cooling Efficiency (EER)

13.3

Pump Energy (Watts)

12.5

Ground Source Heat Pump Well Well Type

Vertical

Number of Wells

3

Well Depth (ft.)

Figure 27. Ground Source Heat Pump (GSHP) operational diagram

150

Table. 9. Ground Source Heat Pump (GSHP) specifications

F. Solar Thermal Solar thermal has proven to be another effective strategy in reducing dependence on fossil fuels by utilizing the solar energy. By using the sizing tool of Solar Rating & Certification Corporation, the 75 gallon solar hot water system with 4 solar thermal panels is selected. The configuration of the system is revealed in Figure Q. Detailed information of the solar thermal collectors is revealed in Table Y. As revealed in Figure K, the panels are tilted to be 40.5 degrees on the north part of the roof so it will not cast shading on PV panels. Various orientations have been tested and not significant effect is identified. Therefore, the orientation of the house, which is south-east, is also used as the orientation of the solar thermal panels. Considering the cost and capacity, the 75 gallon 0.68EF water hot tank is still used as the backup to the solar hot water system, instead of instantaneous tankless hot water heater. By implementing the Solar hot water system, the annual water heating energy consumption is reduced from 29 MMBTU to 12 MMBTU, and the HERS index reduces from 42 to 36.

Multifamily Housing Retrofitting: 1109 Liverpool, Manchester PA

Figure 28. Solar Thermal operational diagram

Collector Type

Double glazing, selective flate plate

Number of Collectors

4

Collector Area Collector Orientation

87.5 Southeast

Collector Tilt

40.5

Storage Volume (gal)

75

Table 10. Solar Thermal system specifications

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G. Photovoltaics Panels

Solar photovoltaic is another technology that utilizes solar energy. Considering the large roof area of the building which is not currently utilized, large opportunities exist to harvest the solar energy by using PV panels. There are mainly three types of solar photovoltaic, mono-crystalline, polycrystalline, and thin film. The mono-crystalline is the one with highest efficiency. However, even within this type of PV panels, efficiency and performance of them vary. The more efficient monocrystalline PV panels can have efficiency as high as 21%, where the average ones have efficiency about 16%. However, price also increases with the increasing efficiency. Therefore, considering the cost, the mono-crystalline PV panels with 16.5% efficiency is selected. The detailed information of this panel is illustrated in Table X. Considering the possible use of the roof for accesses or fire safety reasons, it is assumed that no more than 75% of the roof area will be used for solar PV panel. Since this building is a multifamily building, a modest size of PV arrays of 10.8kW is designed for this property, which will take only 45% of the roof area.

Figure 29.. Rendering of both PV array and Solar Thermal system

75% of Roof Area Total roof area (sf) Number of Modules Array Area (sf) Module Peak Output (W) Total Module Output (W) Module Efficiency Orientation Array Tilt (degrees) Inverter Efficiency

50% of Roof Area

1590.6

1590.6

67 1178 270 18090 16.5% Southeast 0 92%

40 704 270 10800 16.5% Southeast 0 92%

Table 11. Photovoltaic (PV) roof panel specifications

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The horizontally tilted 10.8kW PV system is predicted to produce 37.4 MMBTU of electricity annually, which reduce the total energy consumption from 84.2 to 46.8 MMBTU and HERS index from 36 to 16. If investment is not a restriction and more ambitious energy saving is desired, 18kW PV array which takes 75% of the roof area can be adopted. In that case, the HERS index can be reduced to 2 and the EUI is 4.5 MBTU/sf, which is close to net zero.

H. Integrated Mechanical System: Figure X shows the integrated mechanical systems of the building in the heating mode. Each floor is equipped with an Energy Recovery Ventilator which recovers heat from the exhaust air. The ERV is connected to a dedicated duct that exhausts air from bathroom and kitchen. After preheated, the fresh air is transported to the fan coil in each unit, where it is further heated by the heating coil and then supplied to the space of the room through supply duct. The ground source water loop will be connected to the heat pump of each floor and transfer heat to it. The heat pump will boost the temperature and heat up the air pass through the heating coil. As to the domestic hot water system, the solar hot water system will store hot water heated by the solar energy in the storage tank. A 75 gallon back up hot water tank is also used to ensure sufficient supply of hot water. The solar PV system will generate electricity and meet part of the electricity demand of the building. Surplus electricity from the PV system can be exported to the grid, while the grid electricity can also be purchased to meet the total electricity need.

Figure 30. Integrated mechanical system diagram

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I. Proposed Design Energy Balance Spreadsheet

As revealed in the Energy Balance Spreadsheet, the Site EUI has been reduced to 9.8 MBTU/sf, which is 77.7% less than the US average EUI of single family house. Even without the solar PV system, the Site EUI is still a low as 17.6 MBTU/sf, which is considerably better than the average performance of its counterparts.

Site Energy (include renewable energy consumed) Natural gas, oil, propane, biomass, biofuel Water Heating Electricity (kWh) Lighting & Appliances Heating Cooling Total Energy Consumed (kWh) Renewable Energy Produced on site Imported or derived from onsite processes Purchased Total Renewable Energy

MBTUs

MJ

kWh

MBTUs

MJ

kWh

15,000

15,696

4,395

16,380

17,141

4,799

53,800 12,200 3,200

56,298 12,766 3,349

kWh 15,763 3,575 938

181,037 41,053 10,768

189,442 42,959 11,268

53,044 12,029 3,155

84,200

88,109

24,671

249,238

260,810

73,027

MBTUs 37,400

MJ 39,136

kWh 10,958

125,851

131,694

36,874

37,400

39,136

10,958

125,851

131,694

36,874

Net Balance in kWh (Renewable Energy Provided-Total Energy Consumed) US Residential Avg EUI: 44 MBTU/ft2

Source Energy

13,712

Site EUI (MBTU/ sf)

9.8

36,152

Source EUI (MBTU/sf)

25.9

Table 12. Proposed Design Energy Balance Spreadsheet

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ENERGY PERFORMANCE ANALYSIS

By implementing all the proposed retrofit strategies, the site EUI is reduced by 78.9% and the source EUI is also reduced by 66.8%. As revealed in the Figure 29, space heating is the largest source of energy consumption, while lighting & appliance is the second in the baseline. Space cooling only accounts for 2% of the total energy use, due to the heating dominant climate. However, after all the improvement, the enclosure and heating system has been improved so much that the heating energy consumption in the proposed design only account for 14% of the total energy use (Figure 30) . Because of that, lighting and appliances become the largest energy consumption source. This pattern is observed in most energy efficient homes.

Figure. 31.. Baseline percentage of end use

Baseline Model

Figure..32. Proposed design percentage of end use

PROPOSED DESIGN Model

Site EUI (MBTU/sf)

46.4

Site EUI (MBTU/sf)

9.8

Source EUI (MBTU/sf)

77.9

Source EUI (MBTU/sf)

25.9

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Table 13 shows the effect of each upgrade strategy. As revealed, the new geometry of the building, which reduces the surface area and window area by removing the porch, resulted in certain energy saving and reduced HERS index by 1. Joist insulation is the most effective retrofit strategy in enclosure upgrade, while the floor and ceiling insulation is not. Air sealing that reduces infiltration rate is also predicted to be effective in reducing the energy consumption. As to mechanical system upgrade, implementing Energy Recovery Ventilator (ERV) does not seem to yield considerable energy saving. However, the major reason is that the ERV requires higher fan power to operate to overcome the larger resistance than exhaust fans.

However, if it were compared with balanced mechanical ventilation without energy recovery, implementing the ERV will lead to considerable energy savings. The other three mechanical system upgrades, namely ground source heat pump (GSHP), Solar thermal and PV system, are all predicted to yield high energy and energy cost savings.

Total Annual Consumption (MMBTU)

Annual Energy Cost

HERS Score

221.6

4163

68

192.6

3866

61

197.5

4047

61

New geometry

194.7

4020

60

Wall

184.2

3912

58

Floor

183.4

3904

57

Ceiling

182.2

3891

57

Joist insulation

167

3745

54

Window

163

3697

53

Duct leakage

161.5

3681

52

Infiltration

146.9

3538

50

Lighting

145.5

3462

49

ERV

144.6

3405

48

GSHP

105.5

3261

42

Solar Thermal

84.2

3040

36

PV

46.9

1726

16

Baseline Design

Baseline Design

URA Design

URA design-Wall retrofit URA design-Add exhaust fan

Proposed Design

Table 13. Effectiveness of individual upgrade strategies

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Figure 33 and 34 more clearly show the cumulative and individual effect of the retrofit strategies respectively. As revealed in Figure Y, mechanical system upgrade provides more significant energy saving than the enclosure upgrade. Among all the retrofit strategies, GSHP, Solar PV and Solar system are the most effective. Among all the enclosure upgrade strategies, joist insulation and infiltration are the most effective ones. If the retrofit investment is limited, it is not necessary to implement certain less effective strategies, such as adding insulation to ceiling and floor.

Figure. 33 Cumulative annual energy consumption of individual upgrade strategy

Figure 34. Energy saving of individual upgrade strategy

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Figure 35 and 36 demonstrate the energy cost saving of upgrade strategies both cumulatively and individually. Solar PV panel is predicted to generate an annual energy cost saving of $1,314. However, it is also one of the most expensive retrofit strategies. The 10.8kW PV panel will cost $21,600, of which the simple payback period is 16 years. However, if considering the incentives available for solar PV, such as Pennsylvania Sunshine Solar Rebate Program, which can reduce the investment of PV by up to 35%, the simple payback can be slightly more than 10 years. Although other retrofit strategies seem to produce less energy saving than solar PV, the initial investment might also be lower, therefore could potentially be more preferable to be implemented. Because of the time constraints, the investment of each retrofit strategy and the payback of them are not provided and calculated. It will be helpful to include it in future work.

Figure. 35. Cumulative energy cost saving of individual upgrade strategies

Figure 36. Energy cost saving of individual upgrade strategies

Multifamily Housing Retrofitting: 1109 Liverpool, Manchester PA

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CONCLUSION

In conclusion, the baseline design is slightly more energy intensive than the average U.S. single family buildings. By improving thermal performance of the wall and adding mechanical ventilation, Energy Star Version 3 and URA guideline requirement can be met. If all the proposed upgrade strategies were implemented, the energy performance of the building can be significantly increased. The EUI has been reduced from 46.4 MBTU/sf to 9.8 MBTU/sf, while the HERS index has been reduced from 68 to 16. Opportunities to net the energy consumption of the building to zero also exist, if cost is not a constraining factor. By investigating all the retrofit strategies, ground source heat pump, solar PV, solar thermal, joists insulation, air sealing and wall insulation are the most effective in reducing energy consumption. In addition to energy saving, it is also helpful to include cost of each strategy in future work to help decision-making.

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APPENDIX List of Assumptions Used Dimension of the building:

rate help). Assume the thickness of the insulation is

The height of the first floor is 12 feet, and 10 feet for

10 inches. So the R-value of the insulation will be

upper floors, 8 feet for basement

R31.

•

Thermal boundary:

Assume hard wood flooring (3/4” thick, R=0.68)is used for the base case .

Thermal boundary: from first floor to the top floor,

•

Plywood 5/8”, R=0.77

excluding the basement.

•

Gypsum board (5/8”, R=0.45)

•

Total R value =31

Walls: It is assumed that the existing wall has the same

Ceiling:

construction or equivalent thermal performance as

•

EPDM: R-value is ignored

the retrofitted wall on the first floor.

•

Plywood: 3/4 inch, R-value is 0.94.

•

Assume the exterior color of the wall to be medium.

•

Rigid Insulation is R-38, which consists of 7.5 in

•

Assume the brick is 8 in thick (R=0.88)

•

We assume that the 3.5 inches thick fiberglass batt is

•

2*10 cavity with no insulation.

put in the 2*4 wood studs.

•

Gypsum: 0.5 inch, R=0.45.

Compression factor is 0.684, which is from

•

The color of roof is assumed to be medium.

REMRATE help. The R-value of the insulation after

•

Total R value=38

•

•

Extruded Polystyrene (XPS) (R=5/inch)

compression is 10.26.

•

The framing factor is also from REMRATE help. For 16

Joists:

oc, 10 feet high, the framing factor is 22%.

•

•

One layer of (Plywood 5/8”, R=0.77).

•

Total R value=10

Joists: the area is the sum of upper 3 floors (540.6 sf in total)

•

No insulation for the frame joists.

Floors:

Doors:

•

For all floors, we assume 1 HR floor L501 FC5420 is

•

The dimension of the door: 3 by 8 feet.

used for first floor, second floor and third floor.

•

Doors: We assume the front door are glazing, since

•

•

they are glazing door.

Frame floor: for frame floor, which is the first floor, considering the moisture issues, we assumed that

•

The door on the south façade is 3*8.

fiberglass batts will be used to fill in the 2*10 cavity.

•

Assuming steel door with U=0.22 is used as the rear

The R-value of fiberglass batt is 3.1/inch (from Rem/

Multifamily Housing Retrofitting: 1109 Liverpool, Manchester PA

door.

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APPENDIX Windows: • • •

For 2nd and 3rd floor, the window is low-e 5’ high

Infiltration:

and 3’ width

It is assumed that the infiltration rate has met the Energy

Type: double glazing low-e wood with U=0.30,

Star v-3 requirement (also IECC 2009 Requirement),

SHGC=0.32.

which is 4 ACH50.

For interior shading, we use the default values of 0.85 for Winter and 0.70 for Summer as specified in the RESNET HERS Standards.

URA model assumption: Wall: •

Put wood stud 2 inch away from brick wall. Fill the

Duct:

2 inch gap with polyurethane foam (R=5.6 per inch,

•

We assume 3 return grills for each floor.

according to REMRATE help), and fill the gap with 4

•

We assume supply and return area is 60% and 40%.

inch compressed fiberglass.

•

Total R-value of 20.

Ventilation: For both original design, we assumed that there is no

Mechanical ventilation for IAQ:

mechanical ventilation system for IAQ, and we are as-

•

ment is 60cfm. For retail it is 30 cfm.

suming that natural ventilation is the ventilation strategy for cooling

For second floor and third floor, the flow rate require-

•

The mechanical ventilation is sized based on the fresh air requirement.

Lighting: •

Operation hours: 12 hours.

IECC 2012 require 75% of the lights should be highefficient.

•

•

We are assuming that CFLs account for 80%.

Proposed design assumption: Insulation material: Close cell spray foam (Icynene) R=6.75/inch is used as

Leakage of duct:

the insulation material for all the buildings components.

For duct leakage, we follow the requirement of Energy

It’s environmentally friendly. Closed-cell structure, Syn-

Star v-3, which is shown as follows:

thetic blown.

Total duct leakage shall be ≤ 8 CFM25 per 100 sq. ft. of

Wall:

conditioned floor area.

Put wood stud 2 inch away from brick wall. Fill the 2

Duct leakage to outdoors shall be ≤ 4 CFM25 per 100

inch gap with (Icynene) foam (R=6.75 per inch), and fill

sq. ft. of conditioned floor area.

the gap with 4 inch with (Icynene) too. (R=20 to R=40)

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APPENDIX Floor:

each floor.

Replace the 10 inch fiberglass with 6 inch icynene spray foam (R=31 to R=40.5).

Ground Source Heat Pump: •

Ceiling: Add 4 inch of Icynene insulation in the 10 inch cavity.

3 ton GSHP (WLHP) is chosen (FHP MANUFACTURING COMPANY).

•

GSHP Well: 1 ton (12,000 btu), 1 well of 150feet vertical per ton, spaced 15-25 feet apart.

Leave the rest 6 inch for ducts. (R=38 to R=60)

Joists:

PV:

Assume 2 inch of icynene for joists (R=13.5).

•

Array tilt: horizontal (0 degree).

•

Inverter efficiency: 92%

Windows:

•

Products:

Replace the double-glazing with triple glazing (U=0.22,

•

Yingli Panda 60 Cell Series yl270c-30b (mono-

SHGC=0.26)

crystalline), module efficiency=16.5%, Dimensions: 64.96 in (1650 mm) / 38.98 in (990 mm) / 1.57 in

Duct Leakage:

(40 mm). Peak Power:270W. Cost: $2/Watt.

We assume better duct sealing is implemented and IECC 2012 requirement is met (4 cfm/100 conditioned area total). Assumed leakage to outside is 2cfm/100 conditioned area.

Infiltration: We assume air sealing is implemented and the leakage decreases from 4.0 to 2.5 ACH50.

Lighting: Assume 100% CFLs. (the URA design was assumed to be 80% CFLs).

ERV: Use 1 RENEWAIRE BR70 Energy Recovery Ventilator for

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