H V A C 1 0 1 S y s t e m s
Introduction & Overview Should you care? Mechanical System Types Components & operation Popular Application Key Issues and Design Considerations System Comparisons First Cost Energy Efficiency Summary & Questions 2
Mechanical Systems: Why the big deal? 3
A S H R A E V i s i o n 2 0 2 0 4
Where does the energy go? 5
Mechanical System Types
A. Simple Air Systems- Single Zone One unit, serves one area controlled by one thermostat Easy to understand Can be quite efficient but depends on component efficiency Usually constant volume, fan operates at one speed Can be split components or a packaged unit Maintenance and repairs very elementary Can be networked to a building management system Lifespan of equipment is typically 10-20 years Dehumidification Below Average Lowest First Cost 7
Packaged Terminal Units-PTAC/VTAC V T A C P T A C 8
P T A C - P o p u l a r A p p l i c a t i o n Low rise Hotels Typical Project Need a spot under the window for unit Wall sleeve set during rough framing Horizontal ducting kit for additional sleeping rooms Generally loud Short equipment life (10 yrs)/pull and replace chassis Heat Pump or Electric Heat Very Low cost Key Issues and Design Considerations 9
V T A C - P o p u l a r A p p l i c a t i o n Multifamily Residential Care Typical Project Need a closet on an outside wall and a platform level with sill of outside wall Exterior louver connected directly for each Limited Ducting concealed or exposed Sound control (duct traps, attenuation) Secondary drain pan under unit may be required or a good idea in wood construction Fresh air inlet direct to unit to reduce cost Short equipment life (10 yrs)/pull and replace chassis Heat Pump, Electric, or Gas Heat option Can be used for temporary construction heat or cool (with filter maintenance warranty extension) Low cost Key Issues and Design Considerations 10
S p l i t S y s t e m s 11
S p l i t S y s t e m C o m p o n e n t s 55-110 o F Supply Air Outdoor Unit at grade or on roof. A/C or heat pump 1.5-5 tons Supply Diffusers Ventilation air Refrigeration Piping T 72-75 o F Indoor fan coil- Hor or Vert Gas/electric/no heat Return Air 12
Split System- Popular Applications Multi-family Single family residence Very small single story office building Typical Project 20-150 units Indoor units need inboard/outboard mechanical closets or ceiling space to hang Over 3 ton may required air side economizer to meet the energy code Refrigerant line sets limited to 100 ft for AC or 75 for Heat pump Fresh air inlet direct to indoor unit return- ducted horizontally to wall louver Moderate equipment life (15-20yrs) Heat Pump, Electric, or Gas Heat (infrequent) option Large space on roof for outdoor unit farm (steel) Temporary heat or cool (with filter maintenance warranty extension) Low Cost Key Issues and Design Considerations 13
S m a l l P a c k a g e d R o o f t o p 14
Small Packaged Rooftop Components Outside Air Relief Air Packaged Rooftop Unit 3-50 tons Supply Air 55-105 o F Return Air Free Cooling Economizer Multistage Heat/Cool Hot Gas Reheat for better Humidity Control Constant or Variable Volume T Supply Diffusers 15
Small Packaged Rooftop- Popular Applications Retail Conditioned Warehouse Small single story office building Typical Project Equipment Screening per City ordinance or PUD Concrete pad for vibration control Structural Support Avoid sound sensitive spaces directly underneath Moderate equipment life (15-20yrs) Heat Pump, Electric, or Gas Heat All maintenance is on the roof Condensate discharge to roof, roof drain, or piped indoors Set with crane or helicopter Key Issues and Design Considerations 16
B. Complex Air Systems- Multiple Zone Central Air Handler or Large Packaged rooftop unit serving a large area Comfort Control is accomplished by varying the supply air cfm to zone Each zone has a thermostat for occupant to adjust Airflow to building varies depending on cooling load Heating is typically part of the VAV terminals but can be separate Central Building Automation System Can be air or water cooled- chilled water or DX Electric or Hydronic Heat (Nat. Gas Boiler Plant) Mid-range Cost 17
P a c k a g e d D X V A V R o o f t o p One or multiple large DX VAV rooftop units (25-200 tons) provide supply air to terminal units located in the ceiling plenum Shaft space is required to house vertical supply ducts and a wild return air with flexible zoning path. and limitless heat Most affordable variable air volume solution options. 18
Packaged DX VAV Rooftop- Components Fan Powered VAV Terminal Box With Electric/Hydronic Reheat O.A. E.A. SUPPLY AIR DUCT 55-60 o F R.A. 55-95 o F T T 19
Packaged DX VAV Rooftop- Popular Applications Build to Suit or Developer Low Rise One Story Office Mid Rise Office Medical Office Typical Project 25-300,000 sf Equipment Screening per City ordinance or PUD Concrete pad and/or vibration curb Structural Support and roof access Avoid sound sensitive spaces directly underneath Moderate equipment life (20-25yrs) Electric heat or Gas Heat Can be air cooled or evaporative cooled Condensate discharge to roof, roof drain, or piped indoors Shaft space for ductwork Key Issues and Design Considerations 20
Air Handlers (AHU), Chillers, Boilers Air or water cooled chiller piped to coils in VAV air handlers Air handlers may be roof mounted, located in mechanical penthouses, or in VAV terminal may contain electric heat or hydronic strategically where natural located gas heat is mechanical preferred. rooms. 21
Air Handlers, Chillers, Boilers- Components HEATING WATER PLANT Heating Water Return130 o F Heating Water Supply160 o F PIPING TO VAV BOX REHEAT COILS CHILLED WATER PLANT Chilled Water Return55 o F Chilled Water Supply OA EA 45 o F ENERGY RECOVERY LOW TEMPERATURE AIR UFAD 50-60 o F SA RA 22
Air Handlers, Chillers, Boilers- Popular Application Build to Suit or Multi Tenant Multiple Office Buildings (campus) Institutional and Higher Education Typical Project 200,000 sf and up Central Heating and Cooling Plant (CUP) Cooling Towers at grade or roof Long equipment life (+25yrs) Electric heat or Gas Heat using natural gas condensing boilers (climate driven) Shaft space for ductwork Indoor air handlers or roof mounted Significant mechanical space required Key Issues and Design Considerations Heavy in building automation and environmental control 23
C. Complex Water Systems- Multiple Zone Decentralized- Small air handlers or fan coils connected to a central piping system Retrofit for tight building structures Each zone has a thermostat for occupant to adjust Central Building Automation System Fan Coils with boilers and chillers Water Source Heat Pumps Condenser water cooled VAV units Electric or Hydronic Heat (Nat. Gas Boiler Plant) Mid to High-Range Cost 24
Condenser Water Based Water cooled equipment connected to a common loop. Heat Heat is added rejected to the loop through using supplemental a cooling boilers. A dedicated outdoor air system may be required. tower or ground loop. Space Heating and Cooling is decentralized. 25
Water Source Heat Pumps Small Horizontal, Vertical, Console. Large Vertical Multiple.5 to 5 ton units located above ceiling or in mechanical closets Condenser Units provide water both heating loop and cooling. supply A dedicated outdoor air system is required (DOAS) and return connects all units to a heat sink (cooling tower or ground loop) 26
55-95 o F T SUPPLY AIR DUCT HVAC 101 Water Source Heat Pumps (WSHP) Air Side SUPPLY AIR DUCT 55-95 o F DOAS UNIT VENTILATION AIR DUCT 65-75 o F EA T RA RA 27
Water Source Heat Pumps -Water Side CLOSED CIRCUIT COOLING TOWER 65-75 o F Heating Water Return CONDENSING BOILER 85 o F 95 o F BOILE R PUMP Condenser Water Supply Condenser Water Return SYSTE M PUMP Heating Water Supply 75 o F WATER SOURCE HEAT PUMP POSSIBLE UPGRADES: OPEN TOWER GEOTHERMAL 28
Water Source Heat Pumps- Popular Application 4 or 5 star Hotel Office Buildings (multitenant) High Rise Multi-Family Secondary Education Typical Project Indoor units above ceiling or in closets Cooling Towers at grade or roof Long equipment life (+25yrs) Electric heat or Gas Heat using natural gas condensing boilers Dedicated Outdoor Air Supply- on roof Condenser loop piped through-out building High number of Compressors and filters above ceiling Constant Volume Small ductwork that works with tight plenums Codes beginning to require economizers on larger units High churn cost Key Issues and Design Considerations 29
Self Contained Water Cooled Large Vertical Variable air volume VAV terminals Multiple units located in mechanical rooms, often one per floor Condenser Units provide water cooling loop and ventilation supply air and A separate heating system is required, electric terminals or hydronic return connects all units to a heat sink (cooling tower or ground loop) 30
Self Contained Water Cooled Air Side FAN POWERED VAV TERMINAL BOX WITH ELECTRIC REHEAT O.A. SUPPLY AIR DUCT 55-60 o F 55-95 o F R.A. T T HYDRONIC HEAT ENERGY RECOVERY 31
Self Contained Water Cooled Water Side CLOSED CIRCUIT COOLING TOWER 65-75 o F Heating Water Return CONDENSING BOILER BOILE R PUMP Heating Water Supply 75 o F 75 o F Condenser Water Supply 95 o F Condenser Water Return SYSTE M PUMP SELF CONTAINED WATER COOLED UNIT 32
Self Contained Water Cooled- Popular Application High Rise Office Typical Project Indoor units in mechanical rooms at every floor Decentralized cooling Cooling Towers at grade or roof Long equipment life (+25yrs) Electric heat or Gas Heat using natural gas condensing boilers Fresh air louvers on perimeter Condenser loop piped through-out building Variable Air Volume terminals Minimal shaft space for ductwork Waterside free cooling optional Building automation mostly for zone Key Issues and control Design Considerations 33
Hot water /Chilled Water Based Central heating and cooling plant Chilled and A dedicated outdoor Hot water air system may be Air delivery is decentralized. piping required. Fan Coils come in horizontal, console, and high rise and range in size from 200-1200 cfm extends to small terminals in 34
2-Pipe Fan Coil (2-Pipe)-Components Air Cooled Chiller T 45 o F 55 o F Chilled Water Supply Chilled Water Return 2 Pipe Fan Coil Unit SYSTEM PUMP 35
2-Pipe Fan Coil- Popular Application High Rise Multi Family Typical Project 2 Pipe fan coil with electric heat for each zone Centralized cooling/decentralized Heating Air cooled chiller on roof Long equipment life (+25yrs) Dedicated Outdoor Air System (DOAS) Chilled water loop piped through-out building Minimal shaft space for ductwork Building automation mostly for central equipment and common areas Key Issues and Design Considerations Large quantity of pieces to maintain Temperate and warm climates 36
4-Pipe Fan Coil (4-Pipe) Components Air Cooled Chiller CONDENSING BOILER Heating Water Supply 180 o F 45 o F Chilled Water Supply T 55 o F Chilled Water Return Heating Water Return 160 o F SYSTEM PUMP 4 Pipe Fan Coil Unit SYSTEM PUMP 37
4-Pipe Fan Coil- Popular Application High Rise Multi Family Higher Education Dormitory Typical Project 4 Pipe fan coil for each zone Centralized cooling/centralized Heating Central Utility Plant (local or campus) Long equipment life (+25yrs) Dedicated Outdoor Air System (DOAS) Chilled water and Hot water loop piped through-out building Minimal shaft space for ductwork Building automation mostly for central equipment and common areas Large quantity of pieces to maintain Key Issues and Design Considerations Can be air cooled or water cooled Cold Climate 38
D. Niche Systems New trends in HVAC design to garner LEED points, improve comfort, and/or lower energy. A new way of doing things is Generally looking to achieve often optimum energy over efficiency applied at a premium first cost when introduced into a market by over enthusiastic designers. 39
Underfloor Air Distribution (UFAD) 40
Underfloor Air Distribution- Popular Application Large Office Buildings with open floor plan Typical Project Floor Plenum used for supply air Centralized cooling/centralized Heating Central Utility Plant (local or campus) Multiple Air handling units (1 per floor) Chilled water and Hot water loop piped to air handling units Minimal shaft space for ductwork Building automation mostly for central equipment and common areas Envelope Leakage in plenum Need skin heating system in cold climates Key Issues and Design Considerations Individual manual control of floor diffusers 41
Chilled Beams Exposed ACTIVE Pre-treated Primary Air Supply Air to Room Air handling unit 42
Chilled Beam- Popular Application Large Office Buildings with open floor plan Institutional, Government Typical Project Dedicated Outdoor air system for ventilation ducted to beam and humidity control Centralized cooling/centralized Heating Central Utility Plant (local or campus) Separate overhead air supply to assembly areas (high latent) Chilled water and Hot water loop piped to air handling units Minimal shaft space for ductwork Building dewpoint control critical Excellent for high sensible zones (perimeter) Key Issues and Design Considerations 43
Variable Refrigerant Flow (VRF) Decoupled Ventilation System 44
VRF- Popular Application Buildings with very low floor to floor height Buildings in temperate climates Typical Project Dedicated Outdoor air system for ventilation ducted to spaces Condensing units at grade or on roof Heat recovery using refrigerant All components connected with refrigeration piping Minimal shaft space for ductwork Zoning is expensive Proprietary controls Key Issues and Design Considerations 45
System Comparison and Selection
Systems Comparisons First Cost 35 30 25 Cost ($/sf) 20 15 10 5 0 VTAC Split CV RTU System VAV RTU WSHP Self Contain ed 2-pipe AHU UFAD 4-pipe Chilled Beam System Type VRF GEO 47
System Comparisons- Energy Savings 35 30 Energy Savings (%) 25 20 15 10 5 0 PTAC/ VTAC Split System Small DX RTU 2 PIPE VAV RTU 4 PIPE FCU AHU (ACC) System Type WSHP AHU (WCC) UFAD C Beam VRF GEO 48
System Selection Matrix Energy Utility Rates Gas vs. Electric Energy Code Compliance Comfort Zoning Building Envelope Employee Activity Regional Contractor Expertise Leasing Expectations Weather Rebates and Incentives Maintenance & Reliability Maintenance Staff/Budget Owned or Leased Facility Equipment Useful Life System Integration Floor to floor heights/plenum Loss of leasable floor area Screening or penthouse 49
Summary & Takeaways 1.) Mechanical systems are fun & awesome 2.) System selection is a balance of many factors what is important to the client? 3.) The earlier that owners & clients have good information, the earlier they can make a good decision 50
Questions? 51