High Efficiency Heating and Cooling Systems for Community Colleges Kirk Mescher, PE, LEED AP Principal ICCCFO 2012 1
Learning Objectives for this Session Get acquainted with typical systems used in the Community College setting Understand what comprises a high efficiency system Get to know what supplemental funding sources are available Understand why a central ground source system has cost and operational advantages ICCCFO 2012 2
Building Owner Expectations Simplicity Low maintenance Efficiency Cost Effectiveness Environmentally Green ICCCFO 2012 3
Current Systems Variable Air Volume Systems with reheat zone control Single Zone Air Handling Systems Multi-zone systems Fan Coils / Heat Pumps Variable Refrigerant Flow ICCCFO 2012 4
VAV Systems Standard Large building system from late 1970 s Generally oversized to meet building warm up / cool down needs Claims to take advantage of diversity within the areas served Generally dehumidifies all of the air delivered to the building Controls comfort by adding heat to the dehumidified air Generally consists of A main air handler Chiller Boiler Large distribution duct Variable Air Volume boxes Controls are key to system operation ICCCFO 2012 5
System Complexity = Reduced Efficiency kw = 1.1+0.07+0.07+0.15+0.3+0.16 = 1.85 tons = 1.0-0.03-0.02-0.09-0.05 = 0.81 kw/ton = 2.27 Condenser EER = 5.3 To Room Drive Primary Air 0.07 kw 0 tons Condenser Fans Chiller (Evaporator) Return ~55ºF 1.1 kw +1.0 ton Compressors Chiller Pump Hot Water or Electric Coil Air Valve Series Fan Powered VAV Terminal VAV Terminal VAV Terminal Re-Circulated Room Air VAV Terminal VAV Terminal 0.16 kw -0.05 tons Return Air Fan VAV Terminal VAV Terminal VAV Terminal Fans 0.15 kw -0.03 tons Supply Air VS Fan Motor 0.30 kw -0.09 tons Supply Air Fan Air-Cooled Chiller Inverter Drive Return Air Chilled Water Coil Filter Mixed Air Supply ~45ºF Exhaust Air Re-Circulated Air Chilled Water Ventilation Air Chilled Water Return Chilled Water Supply Central AHU with Variable-Speed Drive Fan Motor 0.07 kw -0.02 tons Chilled Water Pumps Building Loop Pump ICCCFO 2012 6
Single Zone Systems Multiple air handlers serving multiple spaces Each unit can heat or cool as necessary Chilled water or Direct expansion Hot water / steam boilers Simple controls, can make single units Variable air Volume to serve variable needs ICCCFO 2012 7
Fan coil /heat pump Generally a compilation of smaller systems Can be chiller or boiler driven Simple controls Outside air managed through a separate system Fan coils require 4 pipes for simultaneous heating and cooling Heat pumps can accommodate 1 pipe for heating and cooling ICCCFO 2012 8
Variable Refrigerant Flow Refrigerant based fan coil system Newer technology from the Pacific rim Needs separate outside air system Complicated refrigerant management controls 25 tons maximum sizing per system Refrigerant safety concerns ICCCFO 2012 9
Ground Source Best thought of as a heating or cooling source Is a method to recycle energy from the summer to the winter and winter to summer House Bill 4850 may designate as a renewable sustainable resource Is designed based on campus energy needs Is best delivered with high efficiency mechanical systems ICCCFO 2012 10
Geoexchange Renewable Energy Concept 1 kw electricity 4-5 kw Heat Delivered 3-4 kw of Geothermal Energy moved from the Earth ICCCFO 2012 11
Buildings in the Midwest are heating dominated. Heat pumps dump 50% more energy (per delivered ton) during cooling than is removed for heating. Occupied buildings need cooling to temperatures for 30-40ºF. (<25% of the total hours are below these conditions) ARE THEY? ICCCFO 2012 12
Building Energy Profile ICCCFO 2012 13
One Pipe Loop distributed primary secondary loop T sequencer Attributes Demand Fluid Control Secondary pump flow control Little loop temp control Unit by unit diversity No flow regulators Low system pump head Primary pump can be sized for BLOCK load COnditions No drive/pump/static control head inefficiency Challenges Temperature control Pipe Length/ pressure loss Last Heat pump will have warmer/cooler water ICCCFO 2012 14
Heat Recovery Anyone???? sequencer Attribute One pipe loop allows heat pumps to recover energy from the other units on the system. Cooling units add heat to the loop, heating units extract heat T It doesn t take VRF to have heat recovery. ICCCFO 2012 15
The Lake Land Concept Central Loop system 1. Take advantage of Building diversification 2. Loop pumps, back up heat and cooling located in power house ICCCFO 2012 16
Design Considerations Major Advantage to central systems-diversity Effective use of Ground Coupling Pumping efficiency Utility flexibility Central pumping or diversified Central heat rejection/addition or diversified Heating and cooling generation efficiency COP and EER considerations Heating and cooling delivery efficiency ICCCFO 2012 17
Main loop suitable for: 10 Pipe (2000 gpm 800 tons) 12 pipe (3500 gpm 1450 tons) Lake Land Area Community College 12ºF S1 S2 SYSTEM DIAGRAM TC TC TC TC 12ºF Future GCHX S2 S1 12ºF S2 S1 ICCCFO 2012 18
Lake Land Loop Diagram ICCCFO 2012 19
West Field Extension ICCCFO 2012 20
Central Systems Building central systems Adaptable to conventional systems Chilled Beams Fan coils/ Unit Ventilators VAV (Delivery efficiency is a concern here) Single Zone Centralized maintenance Campus central systems Campus wide diversity Utility utilization ICCCFO 2012 21
Central system issues System EER and COP Affected by temperatures, system delivery efficiency and pumping Chilled water delivery 40-45 F water (EER) Additional heat transfer surface Hot water delivery Remember the 2 nd law of thermodynamics (COP) 120F water (refrigeration limitation) Line loss significance Cascade refrigeration (180F) Additional heat transfer Pumping Major component of system efficiency ICCCFO 2012 22
Lake Land Community College System Diagram Main loop suitable for: 10 Pipe (2000 gpm 800 tons) 12 pipe (3500 gpm 1450 tons) 12ºF S1 S2 TC TC ICCCFO 2012 23
Systems Supported at Lake Land Distributed heat pumps VAV with Terminal Reheat 4 Pipe fan coils Chilled Beam with dedicated outside air delivery Outside air Delivered to space Individual space heating and cooling Humidity controlled by OA ICCCFO 2012 24
Electric Use in Buildings % Change Comments Buildings Original W/ft 2 Renovation After W/ft 2 Northwest 2.81 2.20-21.7% Field House 2.91 2.25-22.6% V0-Tech 5.50 (est.) 5.06-8% West Building 4.80 2.80-41.6% Added dental to building usage Added 10,000 ft 2 Added 57,364 ft 2 ICCCFO 2012 25
Considerations 1. Heating is proportionally delivered from central plant 2. Cooling is proportionally delivered from the central plant 3. 2011 Energy usage is metered at the building 4. Central plant will come offline in 2013 ICCCFO 2012 26
System Funding DCEO Energy Efficiency funding for those in Com Ed or Ameren service areas ICECF Funding for Innovative HVAC systems 1/3 of Ground source differential cost (90K cap) Third party financing Leasing of Ground Loops Advanced depreciation 10% tax credit ICCCFO 2012 27
? Questions?????????? ICCCFO 2012 28