Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 1 HVAC?

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1 HVAC SYSTEMS OVERVIEW Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 1 HVAC? HVAC is an acronym that stands for heating, ventilating, and air-conditioning Please pronounce this as 4 separate letters H V A C Not H-Vac Not HEEVAC Denotes an active climate control system An HVAC system should embody the concept of air-conditioning as defined by ASHRAE (see slide #4) In practice, for most larger building projects HVAC AC a Heevac? Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 2 1

2 (H) HEATING & (V) VENTILATING Heating is the process of increasing temperature (typically of air, but perhaps MRT) Some systems do only this (in response to climate and design intent); they would be properly called heating systems Ventilating is the process of moving air (often exhausting it, but perhaps just circulating it) Some systems do only this (in response to climate and design intent); they would be properly called ventilating systems Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 3 (AC) AIR-CONDITIONING According to ASHRAE, an air-conditioning system is a system that can simultaneously control Air temperature (dry bulb) Air relative humidity Air speed (distribution) Air quality (cleanliness +) The quality of control is not explicitly defined, but the definition does not imply precise, pin-point accuracy (in other words, there can be just-barelyacceptable AC systems as well as outstanding AC systems) These four factors are almost what is required for thermal comfort and acceptable IAQ. MRT, however, is missing from the list, and is assumed (by ASHRAE) to be properly controlled by architectural design decisions most, but not necessarily all, HVAC systems should be able to deliver thermal comfort and acceptable IAQ (if properly coordinated, designed, installed, and operated) Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 4 2

3 WHY HVAC? No owner really wants active components ducts, pumps, diffusers, fans, (these are not design intents) An owner wants outcomes: Thermal comfort Indoor air quality Process control, employee productivity, Energy efficiency, greenness, Low costs Few complaints An HVAC system is commonly an appropriate (and often necessary) method for achieving these outcomes Think passive first, but often project context and climate conditions (beyond ignorance or laziness) will demand active Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 5 HVAC DESIGN PROCESS Within the structure of the typical project design phases, the HVAC designer/team should address: Design intent Design criteria Commissioning System conceptualization Design methods Conceptual verification Implementation methods Numerical verification Commissioning Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 6 3

4 HVAC Design Efforts in Traditional Context Conventional Design Process HVAC Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 7 HVAC Design Efforts in Traditional Context Conventional Design Process scope of effort footprint & form decisions: hard to change almost all basic decisions: hard to change HVAC make it work Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 8 4

5 HVAC Design Efforts in IBD* Context * Integrated Building Design Process HVAC concepts HVAC designed HVAC optimized Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 9 HVAC Design Efforts in BIM* Context * Building Information Modeling traditional CAD BIM building floor plan, with mechanical room building floor plan, with mechanical room A box that serves as a footprint placeholder for a real air-handling unit (with only spatial attributes) A box that serves as a footprint and information link for an air-handling unit (with numerous attributes) Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 10 5

6 HVAC SYSTEMS: MAJOR CLASSIFICATIONS Local system Serves one space (and is typically physically located in the space being conditioned) Central system Serves multiple spaces (and is usually housed in none of the conditioned spaces) District system Serves multiple buildings (will be seen as a central system within each building; the district terminology denotes a broad distribution of heating/cooling effect to several central systems) Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 11 LOCAL HVAC SYSTEM CHARACTERISTICS May be a heating, ventilating, cooling, or air-conditioning system Typically serves the space within which it is located Typically serves only one space (when asked to serve more, such a system usually becomes ineffective) Common in several building types (usually residential) Local occupant control can be a plus (the system can be inactive when not needed) or a minus (hard to control with central intelligence) Usually not linked into a central control system The equipment (unit) is essentially the system Not necessarily small (can, for example, be a rooftop unit for a large warehouse) Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 12 6

7 LOCAL HVAC SYSTEM EXAMPLES wood-burning stove (heating only) window AC units (air-conditioning) electric space heater (heating only) Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 13 LOCAL HVAC SYSTEM EXAMPLES typical hotel, motel, apartment through-the-wall AC unit rooftop AC unit (extent of ductwork defines system as local or central) Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 14 7

8 CENTRAL HVAC SYSTEM CHARACTERISTICS May be a heating, ventilating, cooling, or air-conditioning system Serves multiple spaces (at least 2, maybe 12, maybe 1200) Major equipment is usually located in a service space (or spaces) or on a roof Common in many building types (residential, office, educational, commercial) Usually has a centralized control system The numerous equipment components comprising the system are assembled on site Not necessarily large (but may be huge) Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 15 CENTRAL SYSTEM CLASSIFICATIONS All-air Only air (in ductwork) is distributed to the various spaces for heating/cooling effect Air-water Both air and water (in ductwork and in piping) are distributed to the spaces for heating/cooling effect All-water Only water (in piping) is distributed to the spaces for heating/cooling effect There are also a few hard-to-classify arrangements Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 16 8

9 CENTRAL HVAC SYSTEM EXAMPLES All-air system All-water system Air-water system Hard-to-categorize system Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 17 CENTRAL HVAC SYSTEM EXAMPLES all-water heating system all-air air-conditioning system Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 18 9

10 DISTRICT HVAC SYSTEM CHARACTERISTICS Large equipment can provide very high full-load efficiency Careful operation can maintain high efficiencies under partload operations Bulk energy purchase can substantially reduce fuel costs Highly centralized equipment allows for easier ongoing maintenance and tune-ups Often the equipment is of such high capacity that a skilled operator is required to run it the same person can optimize its use (perhaps even hour-by-hour) Large equipment is removed from individual buildings, freeing up space for functional use (or reducing the gross square footage) The scale of operations often permits the use of innovative strategies such as dual fuels, combined heat and power [CHP], fuel cells Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 19 DISTRICT HVAC SYSTEM EXAMPLES source + extensive distribution serve central system A & central system B & source heating/cooling plant steam/chilled water piping tunnel distribution building with central HVAC steam tunnel access/vents Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 20 10

11 A DEEPER LOOK AT LOCAL AND CENTRAL SYSTEMS parts and options determine the whole Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 21 LOCAL HVAC SYSTEMS FUNCTIONAL PARTS a unit is THE part (the system is a self-contained package) Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 22 11

12 CENTRAL HVAC SYSTEMS FUNCTIONAL PARTS Source components: these generate heating and/or cooling effect more later Distribution components: these carry heating/cooling effect from the source to the various loads [spaces] more later Delivery components: these introduce heating/cooling effect into the spaces more later Control components: these are required for effectiveness, efficiency, and safety beyond scope of course Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 23 EXAMPLES OF CENTRAL SYSTEM FUNCTIONAL PARTS All-Air System >> source distribution delivery All-Water System >> base diagrams from Heating, Cooling, Lighting; Lechner Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 24 12

13 USING AIR AS A DISTRIBUTION MEDIUM Air is what is ultimately being conditioned (simple) It s free (economical) It s easy to move (efficient); but lots must be moved for large loads (not efficient) It s easy to deliver heating/cooling effect within a space (just dump air) Air leaks don t damage materials (no worry) Provides substantial IAQ capabilities (ventilation) Not volumetrically effective (requires big ducts) Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 25 AIR DELIVERY ARTIFACTS Register Diffuser Integrated Design? Grille Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 26 13

14 USING WATER AS A DISTRIBUTION MEDIUM Water is an intermediate step relative to what is being provided namely air conditioning (thus, complex) It s cheap (economical) It s fairly easy to move (efficient); and not much needs to be moved (efficient) It s not necessarily easy to deliver heating/cooling effect to a space; doing so requires a water-to-air heat exchanger (complex; can t just dump water in a room) Water leaks may damage materials (some worry) Provides limited IAQ capability (no air exchange) Very volumetrically effective (small pipes) Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 27 WATER DELIVERY ARTIFACTS Valence unit Radiator Radiator Convector Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 28 14

15 RECAPPING SYSTEM ZONES A zone is an area of a building that requires separate control if design intent (typically thermal comfort) is to be met Zones are usually based upon the relative timing of heating/cooling loads Timing of solar gains (east versus south versus west) Occupancy schedules (conference room versus office) Process versus comfort needs (server room versus office) A thermostat is the most common control device for an active system (and it measures ONLY temperature) Proper zoning is critical to system success Zones are the basis for many system classifications Zoning an active system is best done by the architect (an opinion) Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 29 T T T T THE ACTIVE SYSTEM ZONE The 4-zone arrangement shown is one of many possible arrangements. Alternative arrangements can be established by moving, adding, or subtracting thermostats with no change to the underlying floor plan. Such is the nature of active systems. If this building was cooled by a passive cross ventilation system, these zones would not be practical although they might be desirable. Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 30 15

16 THE PASSIVE SYSTEM ZONE cross ventilation air flow Considering cross ventilation, the office and copy room will be on the same zone since they share control (inlet and outlet windows). This may not be wise, but is often physically unavoidable. There are four control devices for this one zone (2 windows and 2 doors) potentially controlled by two people. Such is the nature of passive systems. Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 31 RECAPPING SYSTEM ZONES A zone is an area of a building that requires separate control if design intent (typically thermal comfort) is to be met Zones are usually based upon the relative timing of loads Timing of solar gains (east versus south versus west) Occupancy schedules (conference room versus office) Process versus comfort needs (server room versus office) Switchable devices such as windows/doors are the most common passive system control devices (the sensors are usually the occupants) Zoning is critical to system success Zones are often ignored during passive system design (not a good idea) Establishment of zones should occur before a system is selected Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 32 16

17 ARCHITECTURAL COORDINATION? No architect designed this cooling tower, but some architect allowed it to be placed on his/her building as shown (and seen) the question is why? Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 33 ARCHITECTURAL COORDINATION? Ball State Architecture ENVIRONMENTAL SYSTEMS 2 Grondzik 34 17