BUILDING CORE DESIGN: HVAC DESIGN + LAYOUT Kaitlyn Molner Kayla Fieldhouse 10/09/2013 Environmental Systems II
Identify different ‘thermal zones’ within a typical office floor plan.
Use the information provided in MEEB Table E.25 to identify the appropriate minimum ventilation rate to insure good indoor air quality in office spaces.
“Before attempting to select a heating and cooling system, rough out a zoning scheme for the building, establishing zones that differ from one another in their thermal conditioning requirements and will be controlled separately.” Architect’s Studio Companion page 166 on ‘Zoning a Building for Heating and Cooling.’ 116 people x 5 cfm = 830 cubic feet per minute person
HVAC SIZE AND LAYOUT
Select an HVAC system that will provide adequate ventilation and comfortable conditions in the offices.
a) Approximate space sizes for major heating and cooling equipment using MEEB Table 10.3. 399
Based on the recommended heating and cooling systems for office buildings (SC 164), the Variable Air Volume system was chosen. This system would function best with the open floor plan of the office levels.
CHAPTER 10 LARGE-BUILDING HVAC SYSTEMS
TABLE 10.4 Approximate Space Sizes for Air-Handling Equipment
TABLE 10.3 Approximate Space Sizes for Major Heating and Cooling Equipment
Approximate sizes for all-air sytem in a 60,000 SF office building Total space for boiler/chiller room = 1200 SF Cooling Tower = 200 SF Source: Reprinted by permission from Edward Allen and Joseph Iano, The Architect’s Studio Companion, 4th ed. ©2007 by John Wiley & Sons, Inc.
HVAC SYSTEM TYPES
b) Approximate space sizes for air-handling equipment using MEEB Table 10.4.
Approximate sizes for all-air system in a 60,000 SF office building: Central fan: moves a volume of about 70,000 cfm Source: Reprinted by permission from Edward Allen and Joseph Iano, The Architect’s Studio Companion, 4th ed. ©2007 by John Wiley & Sons, Inc. Main supply/return ducts: each, 42 SF total cross-sectional area Branch supply/return ducts: each, 70 SF total cross-sectional area Fan rooms: 1800 SF total area Fresh air louvers: 180 SF total area Exhaust air louvers: 150 SF total area
HVAC SIZE AND LAYOUT Graphically depict location of HVAC source, distribution, and delivery components in building design. B
Displacement ventilation was implemented in the layout of the Variable Air Volume HVAC system. A 24” raised floor allows room for supply ductwork to deliver air through diffusers in the floor. Return ductwork is suspended from the ceiling with vents to collect air and send it back to the air handling unit or diverted to the exhaust air louver.
36’ Section BB
DESIGN a) Schematic mechanical distribution tree plan of one building story showing HVAC distribution and supply components.
Layout of supply ductwork through raised floor.
Loyout of return ductwork at ceiling level.
DESIGN b) Enlarged floor plan of mechanical room and an enlarged floor plan of the fan room.
Fresh Air Louver
Air Handling unit
Chilling Plant DN
Exhaust Air Louver
The VAV system was chosen based on recommendations for a large office building. We found that the single duct system worked best with the open floor layout. With this system chosen, we thought it best to implement displacement ventilation techniques to provide better air quality to building occupants. We placed the heavy mechanical equipment in the basement and located the air handling unit on the roof to bring fresher air into the system. One challenge we faced was resizing the space designated for the ventilation shaft in the core. Also, the fanroom layout proved to be difficult as we had to decide whether to locate it in the basement, on the roof, or as smaller fan rooms servicing each floor. Once this was decided the penthouse for elevator shafts also had to be accounted for.