Matthew W. Keller
Mechanical Option
Private Residence
Avon, Colorado
Outline
- Existing Building
- Project Overview
- Existing Mechanical System
- Alternate Designs
- Passive Solar Architecture
- Radiant Floor Cooling
- Site-Generated Energy
- Conclusions
- Acknowledgements
- Questions
Existing Building
Project Overview
- September, 2003
- $13.4 Million
Finish Areas
Garage
Mechanical
Crawlspaces
Decks/Patios/Walkways
TOTAL
- $550/ft2
- Project Players
- Rader Engineering, Inc.
12,043 ft 2
1,200 ft2
1,459 ft2
3,796 ft2
5,993 ft2
24,491 ft2
Existing Mechanical System
- Intent:
- “Incorporate state of the art technologies into
proven mechanical systems and equipment to
achieve the ultimate comfort control system.”
- 58 radiant floor zones
- 16 fan coils
- 10 w/ hot water coils
- 15 w/ dx coils
- 15,845 ft2 exterior radiant
- Future Expansion
Existing Mechanical System
Existing Mechanical System
- Humidification
- 7 steam humidifiers
- Total capacity- 41.5 lbs/hr
- Energy Suppliers
- Electricity- Holy Cross Energy
- $0.05/kWh plus demand and customer charge
- Natural Gas- Xcel Energy
- $0.0977/Therm plus service and facility charge
- Initial Cost
- $1,452,042.00- $120.57/ft2 finished area
Alternate Designs
- Intent
- Increase sustainability
- Decrease purchased energy consumption
- Maintain comfort control and aesthetics
- Strategies
- Add Passive Solar Features
- Utilize Radiant Flooring Year Round
- Utilize more site-generated energy
Passive Solar Architecture
- Clerestories
- Glazing Selection
- Thermal Capacity
Passive Solar Architecture
- Clerestories
- Winter Angle
Master Bed.
- =90-(Lat.+23.5)=26.5
- Summer
Angle
Kitchen
- =90-(Lat.-23.5)=73.5
His Office
Passive Solar Architecture
- Design Loads
Heating (MBH)
Cooling (MBH)
Org.
280.3
284.8
New
294.6
296.1
W/shades
294.6
284.5
Passive Solar Architecture
- Increased Envelope
Roof
Stone Wall
Wood Wall
Glazing
Total
Ft2
400
270
470
281
$/Ft2
6
20
8
30
$
2400
5400
3760
8430
$19,990
Passive Solar Architecture
- Glazing
400
350
300
- Design Loads
MBH
250
Cooling
200
Heating
150
100
50
0
O-E
P-E
P-S1
P-S5
- Passive Performance
Arch
Orig.
Pass.
Pass.
Pass.
Glazing
Existing
Existing
Sngt 100
Sngt 500
U
0.36
0.36
0.31
0.35
SC
0.49
0.49
0.59
0.70
F Sol.
0.41
0.46
0.57
0.56
F Mech.
0.59
0.54
0.43
0.44
Passive Solar Architecture
- Thermal Capacity
- Phase Change Wallboard
- Paraffin wax infused
- Cp=9.5 Btu/lb*F
- Melts ~ 76 F
- 14,000 ft2 (5/8”)
- 423 MBTU/Deg.F increase
- $14,000 cost increase
- Effect on Passive Performance
Glazing
Existing
Sngt 100
Sngt 500
U
0.36
0.31
0.35
SC
0.49
0.59
0.70
F
0.46
0.57
0.56
F (ph-ch) Increase
0.47
0.01
0.61
0.04
0.63
0.07
Passive Solar Architecture
- Annual Operating Cost
Arch
Orig.
Pass.
Pass.
Pass.
Glazing
Existing
Existing
Sngt 100
Sngt 500
Heating
$197
$199
$155
$155
Cooling
$1,483
$1,424
$1,690
$1,867
Total
$2,907
$2,827
$3,196
$3,491
Savings
-$80
-$289
-$584
Radiant Floor Cooling
- Less Forced Air Required
- < Fan Energy
- < OA Load
- Decreases MRT
- Allows Higher DB Setpoint
- < Forced Air
- > Free Cooling
Radiant Floor Cooling
- Capacity
- 1.23 Btu/hr*ft2*F
- 16 Btu/hr*ft2
- Minimum Floor Temp: 66 F
- DB Setpoint: 79 F
Radiant Floor Cooling
- New Mechanical System (pass w/ S1)
- Cooling load
- 293.6 MBH (from 305.3 MBH)
- DX Fan Coils and Condensing Units eliminated
- New Equipment
- Fan Coils
- Absorption Chiller
- Increased Heat Rejection
- Modified Operation (2-Pipe)
Radiant Floor Cooling
- Increased Heat Rejection
- Required
- 746.3 MBH (Chiller: 307.3 MBH of mechanical cooling)
- 102.6 MBH (Pool dehumidifiers, pending total enclosure of
pool)
- Available
- 686.4 MBH (Existing Cooling tower)
- Supplemental
- 162.5 MBH of heat rejection is needed
Radiant Floor Cooling
- Supplemental Heat Rejection
- Two radiant zones under exterior water feature
- Designed for 17 GPM and 30 Deg. Temperature drop
- 162.5 MBH rejection achieved with a 21.8 Deg. Temperature
drop
Radiant Floor Cooling
- New Operation/Schematic
Radiant Floor Cooling
- Two-Pipe System Evaluation
- Initial cost
- +$25,400.00
- Absorption Chiller $60,000
- Annual Operation Cost
System
Original
New
Heating
$155
$69
Cooling
$1,690
$658
- Simple Payback = 20 years
Total
$3,196
$1,926
Radiant Floor Cooling
- Radiant Cooling Benefit
- Outdoor Air Load
Mechanical System
Total Space Load (MBH)
Rad. Capacity (MBH)
Supplemental Load (MBH)
CFM
CFM (OA)
OA load (MBH)
Orig.
293.6
-293.6
18821
1882
23
New
293.6
151.6
142
9103
910
11
Site-Generated Energy
- Solar Water Heating
- Solar Electricity Generation
Hot Water Collection
- Evacuated Tubes
- Arrays of 20 &30
- 580 tubes (ft2)
- 1500 gallon storage
Hot Water Collection
- System Comparison
Collector Area
Collector Cost
Output MMBTU
Output Therms
Saved Therms*
Annual Savings
Simple Payback (yrs)
Orig.
350
$7,320
118.1
1181
1389
$136
54
New
580
$40,600
277.1
2771
3260
$319
127
*Assumes 85% seasonal boiler efficiency
Electricity Generation
- Grid Connected
- Shell ST40’s
-
40 Watt output
40 panels
40 degree slope
2 dummies
Cost
Daily Gen. (kWh)
Yearly Gen. (kWh)
Yearly Savings
Simple Payback (yrs)
$17,900
6
2192
$110
163
Conclusions
- Passive Redesign
- Clerestories would be better suited to a climate with
no cooling season
- Thermal capacity benefit
- Radiant Cooling
- Use flooring year round
- 2-Pipe saves energy
- Site-Generated Energy
- Evacuated tube $ increase outweighs performance
benefits
- PV’s not cost effective in existing grid
Thanks to…
- Drew Rader
- President of Rader Engineering
- Prof. Stanley Mumma
- Primary Faculty Consultant
- Fariborz Mahjouri
- Thermo Technology Rep.
- Mark McCray
- RMS Electric Managing Director