Assuming that the Lobbyis mostly glass, and exposedon 3 sides, we will DOUBLE theair requirement in the Lobby...
TOTAL Bldg. Cooling Load:
60 TONSQuick check:Overall Area / Tons = ?20,000 / 60 = 333.3
STEP 1 Determine air flow req'd for each space, for total size of fan unit(s) in tons.
Equation: Area (program) / (sf/ton) = tons req'd for space
Classroom
Museum
Office
Lobby
(Note: not including Freight for now)
8100sf
8100
1100
2700
350sf/ton
450
400
350
/ 23.2 tons
18
2.75
7.7
= Classroom
Museum
Office
Lobby
8100sf
8100
1100
2700
350sf/ton
450
400
350
/ 23.2 tons
18
2.75
15.4
=
This could beadequate for a Lobby that is lessthan 50% glass
59.35 tons
ARE32OL Design 2Museum / Classroom ProjectH.V.A.C. Preliminary Design
M1
Discuss: - Methods of approximating / rough-sizing. Final design process much more involved.- What is a "ton" in HVAC.- Where do these numbers come from (sf/ton by use).- 10 cfm/person outside air included in numbers.
A.H.U / Fan Room (p1 of 2)(approx. sizing using rules of thumb)
ARE32OL Design 2Museum / Classroom ProjectH.V.A.C. Preliminary Design
M2
STEP 2Size the fan unit by approximating the size of the coil.
o T, use 400 cfm/ton (rule of thumb) for air capacity:A. For 20Calculate: 60 tons x 400 cfm/ton = 24,000 cfm
B. Use (rule of thumb) 500 ft./min. for air speed at coil:Calculate: 24,000 cfm / 500 ft/min. = 48 sf
SIZE OF COIL = Hdim x Wdim of A.H.U. = 48 SFLENGTH OF A.H.U. = ~ 2 x COIL SIZE
1 unit: 48 sf = 6.9' .... use 1 unit with 7' x 7' coil x 14'L
2 units: (2) at 24 sf = 4.9' .... use 2 units with 5' x 5' coil ea. x 10'L
3 units: (3) at 16 sf = 4' .... use 3 units with 4' x 4' coil ea. x 8'L
Discuss: - Delta T for Austin: 75F to 55F- Speed at air coil. - Machine access / maintenance.STEP 3
Size the coil area and initial supply duct:
A. Max. velocity for forced air = 1,000 ft/min.
From Step 2: 24,000 cfm / 1000 ft/min = 24sf coil area
1 unit option: 24sf = 4.9' .... use 5' x 5' duct (big!)
2 unit option: 12sf ea. = 3.46' .... use 3.5' x 3.5' duct ea.
3 unit option: 8sf ea. = 2.83 .... use 3' x 3' duct ea.
NOTE: Main Duct dimension can vary up to 2:1 ratio in section.
A.H.U / Fan Room (p2 of 2)(approx. sizing using rules of thumb)
2 x coil width
coil
wid
th~
4' coilcoil
Fan Room - Preliminary Design Plan Size
A.H.U.
min
.
min.min.
Single-unit design: Determine heat req'd for each space, for total heat in btu's.
Equation: Area (program) / (btu/sf) = heat req'd for space5
TOTAL HEAT:543,200 BTU
Classroom
Museum
Office
Lobby
8100sf
8100
1100
2700
28 btu/sf
24
25
35
x 226,800 btu
194,400
27,500
94,500
=
ARE32OL Design 2Museum / Classroom ProjectH.V.A.C. Preliminary Design
M3Boiler / Boiler Room (p1 of 2)(approx. sizing using rules of thumb)
?
Example:HydroTherm ID-85A Boiler500 mbh1'-6"W3'-6"L2'-6"H
divide by 1,000 = ~ 543 mbh unit needed.
Discuss: - BTU values for spaces by use (typ. range 24 - 30).- Units (sizing boiler): 1 mbh = 1000btu- If > 400,00 btu = "boiler" = required 1-hour rated enclosure, and periodic inspections.- If < 200,000 btu = "hot water heater"
Lochinvar 750 btu/hr unit:(Revit module for class)2'-0"W, 2'-4"L, 4'-4"H
Boiler Room - Preliminary Design Plan Size
Boiler
4'-0
" Pumps
for shallow, wide unit:
4'-0"
min.
4'-0"
min.
4'-0"
min.
min
.
Boiler Room - Preliminary Design Plan Size
Boiler 4'-0
" min
.
Pumps
for deep unit:
4'-0"
min.
4'-0"
min.
4'-0"
min.
Multiple-unit design: Total btu reqd. = 543,0003 units under 199btu has advantages.
Lochinvar mfg.
1 unit option: 1 at 500 btu, or
2 unit option: 2 at 300 btu ea., or
3 units option: 3 at 165 btu ea. (199 btu and under = hot water heater status)
ARE32OL Design 2Museum / Classroom ProjectH.V.A.C. Preliminary Design
M4Boiler / Boiler Room (p2 of 2)(approx. sizing using rules of thumb)
Water Heater Room - Preliminary Design Plan Size
3 water heaters
+ 2 pumps in adjacent Chiller Room
4'-0
" min
.
2'-0" Clear, typ.
Manuf: Lochinvar4'-4"H, 2'-4"L, 2'W
STEP 1Determine efficiency / life-span of unit:
Least efficient 10 - 12 year life DX system $3200/ton
25 year life air-cooled system $4800/ton
Most efficient 35 year life water-cooled system $6800/ton
(Source: S.Allen, rules of thumb based on project histories)
ARE32OL Design 2Museum / Classroom ProjectH.V.A.C. Preliminary Design
M5Chiller / Chiller Room(approx. sizing using rules of thumb)
Typically, building will have an air-cooled system if below 300 tons. Water is better (more efficient, longer life-span), typical on big commercial systemsover 300 tons.
STEP 2Choose unit.
60 ton req'd, min. size water unit is 100 ton (oversized, but fine)
York manufacturer, 100 ton unit:138" L (11'-6)44" W (3'-8)73" H
Discuss: - Difference between 3 systems: how they work.
York chiller, 118 tons
Chiller Room Plan - Preliminary Design Size
Chiller
4'-0
"4'
-0"
4'-0"
Plan for Tube replacement
5'-0
"
PUMPS:(2) HW(2) CW(2) condensor
Bell & Gosett1'-5"W, 4'-7"L, 1'-9"H Each
Chiller: McQuay Int.6'-2"W, 11'-8"L, 8'H
ARE32OL Design 2Museum / Classroom ProjectH.V.A.C. Preliminary Design
M6Cooling Tower + Enclosure(approx. sizing using rules of thumb)
Choose unit based on # tons required.
For our project, 60 ton req'd, min. size unit is 100 ton.This oversized, but fine as most units run best at about 75% capacity).
Manuf: Marley, 100 ton unit:12' L4' D10' H
Discuss: 2 How cooling towers work, types of systems, vibration and weight.
Note:Revit files and product pdf:http://seek.autodesk.com/product/latest/agg/spxcoolingtechnologies/SPX-Cooling-Technologies/SPX0001
Cooling Tower Enclosure - Preliminary Design PlanNote: THIS UNIT IS OUTSIDE (ROOF OR GROUND LEVEL)
CoolingTower
8'-0"
Typ. clearanceall around +must be opento sky.
Min. clear around cooling tower: 6' for small units.More clearance for larger units.
Cooling Tower: Morley12'-10"L, 10'-7"W, 10'-2"H
ARE32OL Design 2Museum / Classroom ProjectH.V.A.C. Preliminary Design
M7Electrical and Other Service Rooms(approx. sizing using rules of thumb)
10'-0"
10'-0
"
ELECTRICALTRANSFORMER:3'W X 3'L X 5'H
OUTSIDEDOOR
Main Electrical Room
ELEC. PANELS, SECURITY, TEL, A.V.
CITY ELECT SERVICE: 12,000 VOLTSSTEP DOWN 1ST OUTSIDE, THEN AGAIN INSIDE MAIN ELECT. RM.
MIN
.
MIN.
10'-0"
10'-0
" ELECTRICALTRANSFORMER:6'W X 6'L X 6'H
OUSTIDE PAD-MOUNTEDELEC. TRANSFORMER
3'x3' PAD(METER)
CONC. PAD
10'-0"
10'-0
"
OUTSIDEDOOR
Water Service +Fire Protection Room
MIN.
MIN
.
4'-0"
SecondaryElec. Room
1'-0"
PA
NE
LS
5'-0
" MIN
.
I.T. Room:Many buildings will have one I.T. Room per floor (8'x10')with it's own DX cooling system (for internet servers).
8'-0"8'
-0"
Hydraulic Elev.Machine Room
Pum
p(s)
MIN
.MIN.
For Hydraulic elevators (70' max lift):Locate machine room near bottom landing.(hydraulic fluid pumps and panels)
For Electric elevators:Locate machine room at roof above top of cab.(electric motorized hoist and panels)
MIN.