NIFA Conference 2011

“Solar Innovations”

by Dr. Bing ChenUniversity of Nebraska-LincolnPassive Solar Research Group

Passive Solar Design Principles

Prairie Gold Homes - Base (24’x42’) with 2x4 stud walls

• R-13 walls and R-20 roof, BLC = 8191 BTU/degree-day in Chadron, NE (6774 DD) with indoor design temp of 70°F and outdoor design temp of -3°F.

• Yearly load = 52.6 M BTU or 1535 KWH @ $0.10/kwh = $1535 annual heating bill TIF = 7.2 BTU/DD-SF

Base Case:

• R-30 walls and R-50 roof and 60 SF south windows and R-3 all windows• Yearly load = 12.85 BTU or 3750 KWH or $375 annual heating bill TIF = 1.9• ROI = $6.5K /( $1535-$375) = 5.6 years

Solar Version with Insulation:

PGH Base with additional insulation and larger windows - south view (Cost: $6,500)

PGH Base - sunspace with insulation addition - south view (Cost: $12,500)

• 120 SF sunspace @ $50/SF Yearly load = 12.8 MBTU or 3730 KWH (not insulated), 9.4 BTU or 2750 KWH (insulated)

• Annual heating bill $373 ($275 insulated) ROI = $12.5K / ($1535 - $275) = 10 years

Sunspace (e.g., 15’x8’) Solar Version with Insulation:

Solar Example: Malibu 5 Beach House

- Pacific Coast- $1.3M

http://www.ecofriend.org/entry/eco-architecture-kanner-architects-malibu-5-home-keeps-you-close-to-nature/

Solar Example: Jerry McElroy Home

- Straw bale construction with passive solar- Direct gain- Colorado

http://renewablepowersolarenergy.com/solar-power/passive-solar-design

Modular-Prefab Home Example

http://www.sbkinc.com/weblog/2006/05/the_modular_vacation_home_the.html

- Wee house- Minnesota- $45k

Modular-Prefab Home Example

http://www.thedailygreen.com/green-homes/latest/modular-homes-green-building-gorgeous

- First LivingHome- Designed by Ray Kappe- Certified LEED Platinum- Approx. $230/sq ft

Conclusions

• Passive Solar is a low-cost option that should be considered in residential construction with prefabrication

• Payback times can be 5 years or less

• “Green” and renewables are “in” and may be strong selling points to customers of all economic levels

• Different solar options include different passive techniques, PV for power, active flat plates for domestic hot water heating

References

• Path to Passive: Nebraska’s Passive Solar Primer• Bing Chen et al., 1982• http://www.neo.ne.gov/publications/pathtopassive.htm

• Nebraska Residential Solar Architecture• Bing Chen et al., 1983• http://www.neo.ne.gov/publications/solar_architecture.htm