Air Conditioning Options Winnetka Public School District 36 Winnetka, Illinois November 4, 2016 COMPREHENSIVE AIR CONDITIONING OPTIONS The following are system options to provide a completely air conditioned building. Option A: Variable Refrigerant Flow System (VRF) Crow Island, Greeley, and Hubbard Woods A new Variable Refrigerant Flow (VRF) System will be installed throughout each building. The existing heating and ventilation systems will remain without modification to provide heat and ventilation to the building. The existing unit ventilators will operate to provide required outside air to each space while VRF system provides cooling. This will result in warm, humid air being delivered un-treated to the space while the VRF system maintains space temperature. This operation may cause temperature gradients and/or occupant comfort issues and does not address the aging steam systems in each building. Skokie School A new Variable Refrigerant Flow (VRF) System will be installed throughout the building and will provide year round heating/cooling to each space while the existing Dedicated Outdoor Air System (DOAS) will remain to provide the code required outdoor air. The existing DOAS unit will be coupled with a new VRF or 'DX' system to deliver room neutral, dry air to each space that it serves. The existing hot water finned elements will remain to provide supplemental heating to each space during periods of extreme cold, when the VRF system may not be able to keep up. Utilizing the VRF system for heating will decrease the overall energy cost of heating the building by allowing reduced dependence on the inefficient steam boiler system. Option A: Pros/Cons Pros 1. Least first cost in all cases. 2. Highly efficient during cooling mode. 3. Can be operated in heating mode in a "change over" application to allow for highly efficient heating to 17 deg. F. This will reduce the load on the steam system which is required to provide heat to the unit ventilators for tempered air. 4. Manufacturer's standard web-based controls can reduce temperature control costs.
Page 2 Air Conditioning Options Winnetka Public School District 36 Winnetka, Illinois Cons 1. Unit ventilators must be in operation during occupied periods to provide outside air ventilation to each space. during cooling season, which will be un-tempered. 2. Though VRF system provides heating as well as cooling, heating capacity is supplemental and steam system must be operated to provide tempered air to each unit ventilator and heating to ancillary areas of the building. 3. System option does not address aging and inefficient equipment/systems, including steam boilers/piping. 4. System is inflexible when it comes to modification for future expansion/renovation. Option B: Steam Heating with DX Cooling Crow Island, Greeley, and Hubbard Wood Schools Existing unit ventilators (under-the-window and horizontal suspended style at Crow Island/Greeley and Vertical at Hubbard Woods) will be removed and replaced with new "in-kind" unit ventilators with a new steam heating coil and 'DX' cooling coil. A new air cooled condensing unit will be located on the flat roof above each new unit ventilator to serve each new unit below. Existing steam system will remain and will continue to provide steam to each new system component. This option will be minimally intrusive to the building and will result in a low installation cost, but will keep the aging and inefficient steam infrastructure. Skokie School (N/A) This system is not applicable to Skokie School. Option B: Pros/Cons Pros 1. Low cost of implementation. 2. Ventilation air provided through heating/cooling equipment allows for air to be preheated/cooled and passively dehumidified prior to being delivered to space increasing comfort and decreasing temperature swings. 3. Provides ability to heat/cool spaces during all times. 4. Least intrusive to existing spaces - new refrigerant piping will be routed to roof in small piping enclosure. Cons 1. Higher energy costs associated with system operation. 2. System option does not address aging and inefficient steam piping systems or components. 3. Large quantity of outdoor equipment that needs to be maintained. Option C: 2-Pipe Hot/Chilled Water System Crow Island, Greeley, and Hubbard Wood Schools At each school the existing steam distribution system will be removed and a new water piping distribution system sized for the building cooling requirements will be installed. Each existing unit ventilator will be replaced with a new "in-kind" unit ventilator with a dual temperature heating/cooling coil. A chiller will be installed at each building to serve the cooling needs of that building. The existing steam plants will be removed and replaced with new high efficiency hot water
Page 3 Air Conditioning Options Winnetka Public School District 36 Winnetka, Illinois boilers and all remote steam heating elements will be replaced with "in-kind" hot water elements. The boiler and chiller systems will be coupled together with automatic change over control valves to operate the system in heating or cooling as determined by the building operator or the outside air temperature. This system option will replace the aging and inefficient steam systems throughout each building and reduce the energy costs during the heating season. Skokie School (N/A) This system is not applicable to Skokie School. Option C: Pros/Cons Pros 1. Eliminates aging and inefficient steam piping systems and components. 2. High efficiency hot water boiler system will reduce heating costs. 3. Ventilation air provided through heating/cooling equipment allows for air to be preheated/cooled and passively dehumidified prior to being delivered to space increasing comfort and decreasing temperature swings. Cons 1. System must be operated in a "change over" sequence that can only provide heating or cooling to the entire building at any one time, regardless of each space demand. 2. Large central equipment requires costly annual maintenance agreements. 3. Challenging to find a location for large outside air cooled water chiller that can be made quiet and aesthetic. Option D: Geothermal System Crow Island, Greeley, and Skokie School At Crow Island and Greeley School the existing steam distribution system will be removed. At Skokie School, the existing hot water system distributed throughout the school will remain. A new one-pipe geothermal main will be routed throughout the building and each space will be served by a new vertical stack heat pump unit enclosed in a new drywall enclosure and will provide heating and cooling to each space. At Crow Island/Greeley, a new geothermal DOAS unit will be installed and at Skokie School, the existing DOAS unit will be coupled with a new geothermal heat pump the to provide dehumidified and room-neutral air to each space. At Crow Island/Greeley, a new small high efficiency boiler will be coupled with the geothermal system to raise the one-pipe loop water temperature during periods of extreme cold, while at Skokie School, the existing hot water system will remain active to each of the supplemental heating elements throughout the school. A new geothermal borefield will be installed adjacent to each school. Hubbard Woods The existing steam distribution system will be removed throughout the building. A new one-pipe geothermal main will be routed throughout the building and each space will be served by a new vertical unit ventilator heat pump unit at the same location as the existing that will provide heating, cooling, and ventilation to each space. A new geothermal borefield will be installed adjacent to each school. All existing remote steam heating elements will be replaced with new electric heaters.
Page 4 Air Conditioning Options Winnetka Public School District 36 Winnetka, Illinois Option D: Pros/Cons Pros 1. Eliminates aging and inefficient steam piping systems and components. 2. Highly efficient year round operation will result in lowest energy and maintenance costs of any option. 3. Provides ability to heat or cool individual spaces during all times. 4. Long borefield life and low equipment replacement costs result in lowest life cycle cost of any option. 5. Ventilation air provided through heating/cooling equipment allows for air to be preheated/cooled and passively dehumidified prior to being delivered to space increasing comfort and decreasing temperature swings. 6. No large central equipment to maintain. 7. Simple geothermal heat pump units require minimal maintenance - no more than quarterly filter changes. Cons 1. Highest first cost of system options. The estimated costs of implementing each of these options by school are included in the attached schedules. The cost of an example implementation plan for two of the options is also included in the schedule. COMMON SPACE COOLING CENTER AIR CONDITIONING OPTIONS Carlton Washburne School is completely air conditioned. Its system is not at the end of its life expectancy so it is not included in this analysis. However, efficiency could be improved at Washburne by installing a geothermal heating/cooling system in the future. Each of the other schools in the district has some air conditioned common areas to provide some heat relief to students. Additional areas that are currently heating only were identified to consider for the addition of air conditioning. The locations, recommended systems, and estimated costs of adding air conditioning to these spaces is provided in the attached schedules. A brief description of these options follows. Hubbard Woods Elementary School Basement Kindergarten Room The Kindergarten Room would be cooled by a new replacement "under-the-window" unit ventilator (UV) with DX cooling coil and remote mounted air cooled condensing unit (ACCU). Art Room The Art Room would be cooled by a new replacement "vertical" unit ventilator (UV) with DX cooling coil and remote mounted air cooled condensing unit (ACCU).
Page 5 Air Conditioning Options Winnetka Public School District 36 Winnetka, Illinois Gymnasium The existing indoor air handling unit serving the Gymnasium would be removed and replaced by a new indoor air handling unit (AHU) with a DX cooling coil and an associated remote air cooled condensing unit (ACCU). Crow Island Elementary School Auditorium, Gymnasium The existing indoor air handling units serving the Auditorium and Gymnasium would be removed. Cooling would be accomplished by dedicated packaged rooftop units (RTU) tied into the existing ductwork. The rooftop units would be provided with screening due to the building's status as a historic building. Art Room, Classroom South of Art Room, Children's Museum Each of these rooms would be cooled by a new replacement "under-the-window" unit ventilator (UV) with DX cooling coil and remote mounted air cooled condensing unit (ACCU). Greeley Elementary School Gymnasium The Gymnasium would be cooled by a dedicated packaged rooftop unit (RTU). Skokie Elementary School South & North Gymnasiums Each of the Gymnasiums will be cooled by a new indoor air handling unit (AHU) located in the former 2nd floor shower rooms. Each air handling unit will have a DX cooling coil with associated remote air cooled condensing unit (ACCU). Auditorium The existing supply fan and steam coil serving the Auditorium would be removed and a new custom built-up air handling unit (AHU) would be installed in its place. The air handling unit would have a DX cooling coil with remote air cooled condensing unit (ACCU). Cafeteria The Cafeteria currently has a dedicated outdoor air system providing the code required ventilation. A new Variable Refrigerant Flow (VRF) system would be installed to provide cooling and supplemental heating.
AIR CONDITIONING OPTIONS - HUBBARD WOODS SCHOOL 4-Nov-16 ESTIMATED CONSTRUCTION COSTS: A/C OF ENTIRE BUILDING System Option Steam Remains Steam Removed Area A: DFSS/VRF (Exist. UV to Remain) B: Steam Heating with DX Cooling C: 2-Pipe Hot/ Chilled Water D: Geothermal (Vertical UV HP) $/sf Estimate $/sf Estimate $/sf Estimate $/sf Estimate Mechanical 41622.7 $ 17 $707,586 $ 20 $832,454 $ 30 $1,248,681 $ 30 $1,248,681 Electrical 41622.7 $ 5 $208,114 $ 9 $374,604 $ 5 $208,114 $ 9 $374,604 General Construction 41622.7 $ 1.5 $62,434 $ 5 $208,114 $ 5 $208,114 $ 5 $208,114 Sub-Total $978,133 $1,415,172 $1,664,908 $1,831,399 30% Contingency and Fees $293,440 $424,552 $499,472 $549,420 Total (Work Completed 2017) $1,271,573 $1,839,723 $2,164,380 $2,380,818 Total (Work Completed 2018) $1,335,152 $1,931,710 $2,272,599 $2,499,859 Total (Work Completed 2019) $1,401,910 $2,028,295 $2,386,229 $2,624,852 Total (Work Completed 2020) $1,472,005 $2,129,710 $2,505,541 $2,756,095 ESTIMATED CONSTRUCTION COSTS: COMMON SPACE COOLING CENTERS Location Basement Kinder. (New UV/ACCU) Art Room (New UV/ACCU) Gym (New AHU/ACCU) Grand Total Mechanical Electrical General Construction Sub-Total 30% Contingency and Fees Total Estimate $25,000 $1,500 $500 $27,000 $8,100 $35,100 Estimate Estimate $30,000 $100,000 $1,500 $5,000 $500 $10,000 $32,000 $115,000 $9,600 $34,500 $41,600 $149,500 $226,200 Assumptions: 1. No asbestos abatement is included. 2. Existing steam supply/condensate return piping does not need any repair/replacement where it will remain. 3. $/SF estimates based on past historical project data and do not reflect detailed "per site" contractor estimates of schematic design documents. 4. Contingency and fees consists of 10% design contingency, 10% construction contingency, and 10% fees. 5. Budget cost identified for work completed summer 2017. Escalation of 5% has been added for work completed each subsequent year. Legend: AHU = Air Handling Unit VRF = Variable Refrigerant Flow System DFSS = Duct Free Split System RTU= Rooftop Unit ACCU = Air Cooled Condensing Unit UV = Unit Ventilator HP = Heat Pump ERU = Energy Recovery Unit Page 1
AIR CONDITIONING OPTIONS - CROW ISLAND 4-Nov-16 ESTIMATED CONSTRUCTION COSTS: A/C OF ENTIRE BUILDING System Option Steam Remains Steam Removed Area A: DFSS/VRF (Exist. UV to Remain) B: Steam Heating with DX Cooling C: 2-Pipe Hot/ Chilled Water D: Geothermal (Stack HP w/eru) $/sf Estimate $/sf Estimate $/sf Estimate $/sf Estimate Mechanical 60303.8 $ 17 $1,025,165 $ 25 $1,507,595 $ 30 $1,809,114 $ 35 $2,110,633 Electrical 60303.8 $ 5 $301,519 $ 9 $542,734 $ 5 $301,519 $ 9 $542,734 General Construction 60303.8 $ 1.5 $90,456 $ 5 $301,519 $ 5 $301,519 $ 5 $301,519 Screening -- $15,000 $0 $10,000 $0 Sub-Total $1,432,139 $2,351,848 $2,422,152 $2,954,886 30% Contingency and Fees $429,642 $705,554 $726,646 $886,466 Total (Work Completed 2017) $1,861,781 $3,057,403 $3,148,798 $3,841,352 Total (Work Completed 2018) $1,954,870 $3,210,273 $3,306,237 $4,033,420 Total (Work Completed 2019) $2,052,614 $3,370,786 $3,471,549 $4,235,091 Total (Work Completed 2020) $2,155,244 $3,539,326 $3,645,127 $4,446,845 ESTIMATED CONSTRUCTION COSTS: COMMON SPACE COOLING CENTERS Location Auditorium (New RTU) Gym (New RTU) Art Room (New UV/ACCU) Room South of Art Room (New UV/ACCU) Children's Museum (New UV/ACCU) Estimate Estimate Estimate Estimate Estimate Mechanical Electrical $50,000 $3,000 $60,000 $3,000 $25,000 $1,500 $25,000 $1,500 $25,000 $1,500 General Construction $5,000 $5,000 $500 $500 $500 Screening $5,000 $5,000 $0 $0 $0 Sub-Total $63,000 $73,000 $27,000 $27,000 $27,000 30% Contingency and Fees $18,900 $21,900 $8,100 $8,100 $8,100 Total $81,900 $94,900 $35,100 $35,100 $35,100 Grand Total $282,100 Assumptions: 1. No asbestos abatement is included. 2. Existing steam supply/condensate return piping does not need any repair/replacement where it will remain. 3. $/SF estimates based on past historical project data and do not reflect detailed "per site" contractor estimates of schematic design documents. 4. Contingency and fees consists of 10% design contingency, 10% construction contingency, and 10% fees. 5. Budget cost identified for work completed summer 2017. Escalation of 5% has been added for work completed each subsequent year. Legend: AHU = Air Handling Unit VRF = Variable Refrigerant Flow System DFSS = Duct Free Split System RTU= Rooftop Unit ACCU = Air Cooled Condensing Unit UV = Unit Ventilator HP = Heat Pump ERU = Energy Recovery Unit Page 2
AIR CONDITIONING OPTIONS - GREELEY SCHOOL 4-Nov-16 ESTIMATED CONSTRUCTION COSTS: A/C OF ENTIRE BUILDING System Option Steam Remains Steam Removed Area A: DFSS/VRF (Exist. UV to Remain) B: Steam Heating with DX Cooling C: 2-Pipe Hot/ Chilled Water D: Geothermal (Vertical UV HP) $/sf Estimate $/sf Estimate $/sf Estimate $/sf Estimate Mechanical 44022.9 $ 17 $748,389 $ 20 $880,458 $ 30 $1,320,687 $ 30 $1,320,687 Electrical 44022.9 $ 5 $220,115 $ 9 $396,206 $ 5 $220,115 $ 9 $396,206 General Construction 44022.9 $ 1.5 $66,034 $ 5 $220,115 $ 5 $220,115 $ 5 $220,115 Sub-Total $1,034,538 $1,496,779 $1,760,916 $1,937,008 30% Contingency and Fees $310,361 $449,034 $528,275 $581,102 Total (Work Completed 2017) $1,344,900 $1,945,812 $2,289,191 $2,518,110 Total (Work Completed 2018) $1,412,145 $2,043,103 $2,403,650 $2,644,015 Total (Work Completed 2019) $1,482,752 $2,145,258 $2,523,833 $2,776,216 Total (Work Completed 2020) $1,556,889 $2,252,521 $2,650,024 $2,915,027 ESTIMATED CONSTRUCTION COSTS: COMMON SPACE COOLING CENTER Gym (New RTU) Estimate Mechanical $50,000 Electrical $3,000 General Construction $5,000 Sub-Total $58,000 30% Contingency and Fees $17,400 Total $75,400 Assumptions: 1. No asbestos abatement is included. 2. Existing steam supply/condensate return piping does not need any repair/replacement where it will remain. 3. $/SF estimates based on past historical project data and do not reflect detailed "per site" contractor estimates of schematic design documents. 4. Contingency and fees consists of 10% design contingency, 10% construction contingency, and 10% fees. 5. Budget cost identified for work completed summer 2017. Escalation of 5% has been added for work completed each subsequent year. Legend: AHU = Air Handling Unit VRF = Variable Refrigerant Flow System DFSS = Duct Free Split System RTU= Rooftop Unit ACCU = Air Cooled Condensing Unit UV = Unit Ventilator HP = Heat Pump ERU = Energy Recovery Unit Page 3
AIR CONDITIONING OPTIONS - SKOKIE SCHOOL 4-Nov-16 ESTIMATED CONSTRUCTION COSTS: A/C OF ENTIRE BUILDING System Option Steam Remains Steam Removed Area A: DFSS/VRF (Exist. UV to Remain) D: Geothermal (Vertical UV HP) $/sf Estimate $/sf Estimate Mechanical 98343.9 $ 17 $1,671,846 $ 22 $2,163,566 Electrical 98343.9 $ 5 $491,720 $ 9 $885,095 General Construction 98343.9 $ 1.5 $147,516 $ 5 $491,720 Sub-Total $2,311,082 $3,540,380 30% Contingency and Fees $693,324 $1,062,114 Total (Work Completed 2017) $3,004,406 $4,602,495 Total (Work Completed 2018) $3,154,626 $4,832,619 Total (Work Completed 2019) $3,312,358 $5,074,250 Total (Work Completed 2020) $3,477,976 $5,327,963 ESTIMATED CONSTRUCTION COSTS: COMMON SPACE COOLING CENTERS Location SOUTH GYM (AHU/ACCU in abandoned 2nd floor shower room) NORTH GYM (AHU/ACCU in abandoned 2nd floor shower room) Auditorium (New AHU/ACCU) Cafeteria (VRF) Estimate Estimate Estimate Estimate Mechanical $100,000 $100,000 $125,000 $30,000 Electrical $5,000 $5,000 $5,000 $2,000 General Construction $10,000 $10,000 $10,000 $500 Sub-Total $115,000 $115,000 $140,000 $32,500 30% Contingency and Fees $34,500 $34,500 $42,000 $9,750 Total $149,500 $149,500 $182,000 $42,250 Grand Total $523,250 Assumptions: 1. No asbestos abatement is included. 2. Existing steam supply/condensate return piping does not need any repair/replacement where it will remain. 3. $/SF estimates based on past historical project data and do not reflect detailed "per site" contractor estimates of schematic design documents. 4. Contingency and fees consists of 10% design contingency, 10% construction contingency, and 10% fees. 5. Budget cost identified for work completed summer 2017. Escalation of 5% has been added for work completed each subsequent year. Legend: AHU = Air Handling Unit VRF = Variable Refrigerant Flow System DFSS = Duct Free Split System ACCU = Air Cooled Condensing Unit UV = Unit Ventilator HP = Heat Pump Page 4
TOTAL COST OF COOLING CENTERS: $1,106,950 TOTAL COST TO A/C ENTIRE BUILDING: OPTION A: DFSS/VRF (STEAM REMAINS) School 2017 2018 2019 2020 Total Hubbard Woods $1,271,573 Crow Island $1,954,870 Greeley $1,482,752 Skokie $3,477,976 $8,187,171 OPTION B: STEAM HEATING WITH DX COOLING (STEAM REMAINS) School 2017 2018 2019 2020 Total Hubbard Woods $1,839,723 Crow Island $3,210,273 Greeley $2,145,258 Skokie (Option A) $3,477,976 $10,673,230 NOTE: Skokie School assumes "lowest cost" option is chosen. OPTION C: 2-PIPE HOT/CHILLED WATER (STEAM REMOVED) School 2017 2018 2019 2020 Total Hubbard Woods $2,164,380 Crow Island $3,306,237 Greeley $2,523,833 Skokie (Option A) $3,477,976 $11,472,426 NOTE: Skokie School assumes "lowest cost" option is chosen. OPTION D: GEOTHERMAL (STEAM REMOVED) School 2017 2018 2019 2020 Total Hubbard Woods $2,380,818 Crow Island $4,033,420 Greeley $2,776,216 Skokie $5,327,963 $14,518,417 OPTION E: HYBRID (RECOMMENDED) School 2017 2018 2019 2020 Total Hubbard Woods (Opt. D) $2,380,818 Crow Island (Opt. D) $4,033,420 Greeley (Opt. D) $2,776,216 Skokie (Opt. A) $3,477,976 $12,668,430 Page 5