Multifamily Housing Retrofit: 1109 Liverpool

/[email protected]/

Xiaopeng Ma

Duy Vo

/[email protected]/

MANCHESTER, PA

1109 LIVERPOOL ST.

1 39Multifamily Housing Retrofitting: 1109 Liverpool, Manchester PA

TABLE OF CONTENT

SITE CONTEXTBUILDING INFORMATION

BASELINE MODEL

BASELINE MODEL

URA COMPLIANT MODEL

PROJECT SCOPE OF WORK

A. General Information

A. Existing Floor Plans

A. Building Shape

A. URA Compliant Framed Wall Assembly

C. Baseline Mechanical System

C. Energy Recovery Ventilation System

C. URA Compliant Energy Balance Spreadsheet

E. Infiltration & Air Leakage

E. HVAC System

B. Thermal Boundary

B. Baseline Enclosure System

B. Baseline Enclosure System

B. Exhaust Only Ventilation

D. Lighting & Appliances

D. Infiltration & Air Leakage

F. Baseline Energy Balance Spreadsheet

F. Solar Thermal

4

5

5

6

7

8

9

9

13

13

15

15

16

17

18

19

20

21

22

25

26

26

28


TABLE OF CONTENT

CONCLUSION

APPENDIX

ENERGY PERFORMANCE ANALYSIS

G. Photovoltaic Panels

I. Proposed Design Energy Balance Spreadsheet

List of Assumptions Used

H. Integrated Mechanical System29

30

31

32

36

3738


LIST OF FIGURES & TABLES

Figure 1 . Building Site Indicator Map

Figure 3.. View of the Southern facadeFigure 4. Panoramic view of the building and its surrounding context

Figure 2. View of the Northern facade

Figure 5. Building Overall Thermal BoundaryFigure 6. Project Scope of Work DiagramFigure 7. Rendering of the baseline model in its contextFigure 8. Floor plans for the retrofit proposal done by Robert Baumbach DesignFigure 9. Overall section of the baseline modelFigure 10. Baseline framed floor assembly detailFigure 11. Baseline framed wall assembly detailFigure 12. Baseline framed roof assembly detailFigure 13.. Baseline double-glazed windowFigure 14. Rendering of the URA compliant model in its contextFigure 15. URA compliant framed wall assembly detailFigure 16. Air King Exhaust FanFigure 17. Apollo Exhaust FanFigure 18. Rendering of the proposed design model in its contextFigure 19. Proposed 2nd floor planFigure 20. Proposed 3rd floor planFigure 21. Overall section of the proposed design modelFigure 22. Proposed framed floor assembly detail

Figure 24. Proposed framed roof assembly detailFigure 23. Proposed framed wall assembly detail

Figure 25.. Proposed triple-glazed windowFigure. 26. Renewaire BR7O ERVFigure 27. Ground Source Heat Pump (GSHP) operational diagram Figure 28. Solar Thermal operational diagramFigure 29.. Rendering of both PV array and Solar Thermal systemFigure 30. Integrated mechanical system diagramFigure. 31.. Baseline percentage of end useFigure..32. Proposed design percentage of end use

Figure. 35. Cumulative energy cost saving of individual upgrade strategiesFigure 36. Energy cost saving of individual upgrade strategies

Figure. 33 Cumulative annual energy consumption of individual upgrade strategyFigure 34. Energy saving of individual upgrade strategy

Table 1. Baseline HVAC system detailsTable 2. Baseline Model Energy Balance SpreadsheetTable 3. Exhaust fan details

Table 5. ERV Specifications. Table 6. Heating and Cooling design loads

Table 4. URA Compliant Model Energy Balance Spreadsheet

Table 8. Air Source Heat Pump (ASHP) effectiveness analysisTable. 9. Ground Source Heat Pump (GSHP) specificationsTable 10. Solar Thermal system specifications

Table 7. Air Source Heat Pump (ASHP) specifications

Table 11. Photovoltaic (PV) roof panel specificationsTable 12. Proposed Design Energy Balance SpreadsheetTable 13. Effectiveness of individual upgrade strategies

List of Tables

List of Figures


§SITE CONTEXT The building investigated in this study is located at 1109 Liverpool street, Manchester, PA. Manches-ter 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


A. General Information 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.

BUILDING INFORMATION

Figure 3.. View of the Southern facade

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

Figure 2. View of the Northern facade


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


Baseline Model

SCOPE OF WORK

URA COMPLIANT Model

PROPOSED DESIGN Model

(Created using the information provided by Robert Baumbach Building Design as well as

some of our own assumptions)

Baseline model adjusted to meet URA design guideline

Model created to both meet URA guideline and net to zero

PROJECT SCOPE OF WORK

Figure 6. Project Scope of Work Diagram

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

Figure 7. Rendering of the baseline model in its context


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.

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:• FramedFloorAssembly• FramedWallAssembly• FramedRoofAssembly• GlazingType

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


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.


4 in. fiberglass batt insulation

5/8 in. plywood sheathing

1/2 in. gypsum


3/4 in. wood flooring

2x10 floor joists

10 in. fiberglass batt

Figure 10. Baseline framed floor assembly detail

Figure 11. Baseline framed wall assembly detail


4 in. fiberglass batt insulation

1/2 in. gypsum

4in. framed wall stud


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.

Window Properties Values

U-value 0.3SHGC 0.32Tvis 0.5

d. Baseline glazing typeBecause 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.

Figure 13.. Baseline double-glazed window

Figure 12.. Baseline framed roof assembly detail

7.5 in. rigid insulation

EPDM rubber roofing

2x10 roof joists

3/4 plywood sheathing



C. Baseline Mechanical SystemFor 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 Type Capacity Served Space No. of Units

Heating92 AFUE Gas

Furnace 3 ton 1 for Each Floor 3

Cooling

13 SEER Air Conditioner

3 ton 1st Retail Floor 1

13 SEER Air Conditioner

2 ton 2nd & 3rd Floors 2

Domestic Hot Water (DHW) 0.68EF Gas Boiler 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 STARCost: $99.98Airflow Efficiency: 102 CFM/Watt


WhirlpoolGold30-in2.1cuft/3.9cu.ftDoubleOvenGas

RangeCost: $1349

Whirlpool 24-inBuilt-InDishwasher(Black)ENERGYSTARCost: $329EnergyConsumption: 282 kWh/yr

Frigidaire14.8cu.ft.(TopFreezerRefrigerator)

Cost: $499EnergyConsumption: 355kWh/yr

Samsung3.6cu.ftLargeCapacityFrontLoadWasher

Cost:$846WasherLER: 94kWh/yr

Roper 6.5cuftGasDryer(White)

Cost:$499EfficiencyFactor: 2.67

We’vemadetheassumptionthat80%ofthebuilding’slight

bulbsareCFLs


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.

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

Electricity (kWh) kWh

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

Imported or derived from on-site processes

Purchased

Total Renewable Energy 0 0 0 0 0 0

Net Balance in kWh (Renewable Energy Provided-Total Energy

Consumed)64,900 108,898

US Residential Avg EUI: 44 MBTU/ft2

Site EUI (MBTU/sf)

46.4 Source EUI (MBTU/sf)

77.9

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.

Table 2. Baseline Model Energy Balance Spreadsheet


URA COMPLIANT MODEL

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


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.

Figure 15. URA compliant framed wall assembly detail

2 in. spray polyurethane insulation applied directly onto the brick wall

1/2 in. gypsum

4in. framed wall stud

4 in. fiberglass batt insulation inserted between 2x4 studs

Existing brick masonry wall

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.


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 require-ment is 60cfm. For retail floor it is 30 cfm.

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 Floor2nd & 3rd

Floors

Figure 16. Air King Exhaust Fan

Figure 17. Apollo Exhaust Fan

Table 3. Exhaust fan details


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

Electricity (kWh) kWh

Lighting & Appliances 57,900 60,588 16,965 194,834 203,879 57,086

Cooling 4,700 4,918 1,377 15,816 16,550 4,634


Renewable Energy MBTUs MJ kWh MBTUs MJ kWh

Produced on site 0 0 0 0 0 0


Purchased

Total Renewable Energy 0 0 0 0 0 0

Net Balance in kWh (Renewable Energy Provided-Total Energy

Consumed)57,868 104,882


Site EUI (MBTU/sf)

41Source EUI (MBTU/sf)

75

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.

Table 4. URA Compliant Model Energy Balance Spreadsheet


PROPOSED DESIGN MODEL

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


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

Living room connected to dining room and kitchen

1st BedroomWC2nd Bedroom

Living room connected to dining room and kitchen

1st BedroomWC2nd Bedroom

Figure 19. Proposed 2nd floor plan

Figure 20. Proposed 3rd floor plan

A. Building Shape


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 unitsWe 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.

Figure 21. Overall section of the proposed design model

B. Baseline Enclosure System Below are the following assemblies that we investigated and modeled:• FramedFloorAssembly• FramedWallAssembly• FramedRoofAssembly• GlazingType


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

2x10 floor joists

Figure 22. Proposed framed floor assembly detail


Figure 24. Proposed framed roof assembly detail

Figure 23. Proposed framed wall assembly detail

2 in. icynene applied directly onto the brick wall

4 in. icynene applied in between the 2x4 studs

1/2 in. gypsum

2X4 sill plate

Existing brick wall

2x10 roof joists

4 in. blown icynene

7.5 in. rigid insulation

White EPDM roofing




Window Properties Values

U-value 0.22

SHGC 0.26

Tvis 0.45

d. Proposed glazing typeWe 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 triple-glazed, moderate solar gain low-e glass with argon filled from the double-glazed type previously proposed in the baseline

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.

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

Figure 25.. Proposed triple-glazed window


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

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

Figure. 26. Renewaire BR7O ERV Table 5. ERV Specifications.

D. Infiltration & Duct LeakageInfiltration 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 belowDuct 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.

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


Heating Design load

(kBTU/yr)

Cooling Design load

(kBTU/yr)

ASHP Heating

load

ASHP Cooling

load

ASHP Heating efficiency

(HSPF)

ASHP Cooling efficiency

(SEER)1st floor 11.2 6.5 12.6 11.9 10 202nd floor 11.5 7.7 12.6 11.9 10 203rd floor 13.3 8.8 13.6 12 9.25 17.8

Table 7. Air Source Heat Pump (ASHP) specifications

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.

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.

Base HVAC system

ASHP Reduction % Reduction

Total Annual Energy Consumption (MMBTU)

144.6 117.6 27 18.7%

Annual Energy Cost ($) 3405 3684 -279 -8.2%HERS Score 48 49 -1 -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.


3 ton AQUARIUS WW036-3 GSHPHeating 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.) 150

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

Figure 28. Solar Thermal operational diagram

Collector TypeDouble glazing,

selective flate plate

Number of Collectors 4

Collector Area 87.5Collector Orientation Southeast

Collector Tilt 40.5

Storage Volume (gal) 75

Table 10. Solar Thermal system specifications


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 50% of Roof AreaTotal roof area (sf)

1590.6 1590.6

Number of Modules 67 40Array Area (sf) 1178 704

Module Peak Output (W) 270 270Total Module Output (W) 18090 10800

Module Efficiency 16.5% 16.5%Orientation Southeast Southeast

Array Tilt (degrees) 0 0Inverter Efficiency 92% 92%

Table 11. Photovoltaic (PV) roof panel specifications


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.

Figure 30. Integrated mechanical system diagram

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.


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) Source Energy

Natural gas, oil, propane, biomass, biofuel MBTUs MJ kWh MBTUs MJ kWh

Water Heating 15,000 15,696 4,395 16,380 17,141 4,799

Electricity (kWh) kWhLighting & Appliances 53,800 56,298 15,763 181,037 189,442 53,044

Heating 12,200 12,766 3,575 41,053 42,959 12,029Cooling 3,200 3,349 938 10,768 11,268 3,155


Renewable Energy MBTUs MJ kWhProduced on site 37,400 39,136 10,958 125,851 131,694 36,874


PurchasedTotal Renewable Energy 37,400 39,136 10,958 125,851 131,694 36,874

Net Balance in kWh (Renewable Energy

Provided-Total Energy Consumed)

13,712 36,152


Site EUI (MBTU/

sf)9.8

Source EUI

(MBTU/sf)25.9

Table 12. Proposed Design Energy Balance Spreadsheet


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.

Site EUI (MBTU/sf) 46.4

Source EUI (MBTU/sf) 77.9

Baseline ModelSite EUI

(MBTU/sf) 9.8

Source EUI (MBTU/sf) 25.9

PROPOSED DESIGN Model

Figure. 31.. Baseline percentage of end use Figure..32. Proposed design percentage of end use


Total Annual Consumption

(MMBTU)

Annual Energy Cost HERS Score

Baseline Design Baseline Design 221.6 4163 68

URA Design

URA design-Wall retrofit

192.6 3866 61

URA design-Add exhaust fan

197.5 4047 61

Proposed Design

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

Table 13. Effectiveness of individual upgrade strategies

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.


Figure. 33 Cumulative annual energy consumption of individual upgrade strategy

Figure 34. Energy saving of individual upgrade strategy

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. 35. Cumulative energy cost saving of individual upgrade strategies

Figure 36. Energy cost saving of individual upgrade strategies

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.


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.


APPENDIX

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

upper floors, 8 feet for basement

Thermal boundary:Thermal boundary: from first floor to the top floor,

excluding the basement.

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

construction or equivalent thermal performance as

the retrofitted wall on the first floor.

• Assume the exterior color of the wall to be medium.

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

• We assume that the 3.5 inches thick fiberglass batt is

put in the 2*4 wood studs.

• Compression factor is 0.684, which is from

REMRATE help. The R-value of the insulation after

compression is 10.26.

• The framing factor is also from REMRATE help. For 16

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

• One layer of (Plywood 5/8”, R=0.77).

• Total R value=10

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

used for first floor, second floor and third floor.

• Frame floor: for frame floor, which is the first floor,

considering the moisture issues, we assumed that

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

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

rate help). Assume the thickness of the insulation is

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

R31.

• Assume hard wood flooring (3/4” thick, R=0.68)is

used for the base case .

• Plywood 5/8”, R=0.77

• Gypsum board (5/8”, R=0.45)

• Total R value =31

Ceiling:• EPDM: R-value is ignored

• Plywood: 3/4 inch, R-value is 0.94.

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

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

• 2*10 cavity with no insulation.

• Gypsum: 0.5 inch, R=0.45.

• The color of roof is assumed to be medium.

• Total R value=38

Joists:

• Joists: the area is the sum of upper 3 floors (540.6 sf

in total)

• No insulation for the frame joists.

Doors:• The dimension of the door: 3 by 8 feet.

• Doors: We assume the front door are glazing, since

they are glazing door.

• The door on the south façade is 3*8.

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

door.

List of Assumptions Used


APPENDIX

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

and 3’ width

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

SHGC=0.32.

• 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.

Duct:• We assume 3 return grills for each floor.

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

Ventilation:

For both original design, we assumed that there is no

mechanical ventilation system for IAQ, and we are as-

suming that natural ventilation is the ventilation strategy

for cooling

Lighting:• IECC 2012 require 75% of the lights should be high-

efficient.

• We are assuming that CFLs account for 80%.

Leakage of duct:For duct leakage, we follow the requirement of Energy

Star v-3, which is shown as follows:

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

conditioned floor area.

Duct leakage to outdoors shall be ≤ 4 CFM25 per 100

sq. ft. of conditioned floor area.

Infiltration:It is assumed that the infiltration rate has met the Energy

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

which is 4 ACH50.

URA model assumption:Wall: • Put wood stud 2 inch away from brick wall. Fill the

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

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

inch compressed fiberglass.

• Total R-value of 20.

Mechanical ventilation for IAQ:• For second floor and third floor, the flow rate require-

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

• The mechanical ventilation is sized based on the

fresh air requirement.

• Operation hours: 12 hours.

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

the insulation material for all the buildings components.

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

thetic blown.

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

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

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


APPENDIX

Floor:Replace the 10 inch fiberglass with 6 inch icynene spray

foam (R=31 to R=40.5).

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

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

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

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

SHGC=0.26)

Duct Leakage: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

each floor.

Ground Source Heat Pump:• 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.

PV:• Array tilt: horizontal (0 degree).

• Inverter efficiency: 92%

• Products:

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

crystalline), module efficiency=16.5%, Dimensions:

64.96 in (1650 mm) / 38.98 in (990 mm) / 1.57 in

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

Multifamily Housing Retrofit: 1109 Liverpool

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Transcript of Multifamily Housing Retrofit: 1109 Liverpool