Finding Residential Energy Solutions through Energy Modeling
A Case Study of Fort Belknap IHS Staff Quarters, Ft. Belknap MT
Michael R. Young, P.E.Civil EngineerDivision of Engineering Services - Seattle Indian Health Service
Objectives
To illustrate methods to achieve energy efficiency in low-rise residential buildings.
To demonstrate most effective measures to save energy over the life cycle of the system.
To help save money to the occupants.
Overview
Federal Regulations Case Study: Fort Belknap, MT Results:
Energy Consumption Annual Utility Bills Life Cycle Cost Analysis
Recommendations: Design
Emerging Energy Regulations EPAct 2005 (Public Law 109-58)
Federal Leadership in High Performance and Sustainable Buildings MOU
EISA 2007
Executive Order 13423Strengthening Federal Environmental, Energy, and Transportation Management
10 CFR 433, 434, 435
Executive Order 13514
Federal Leadership in Environmental, Energy, and Economic Performance
Requirements of 10 CFR 435
Meet ICC International Energy Conservation Code, 2004 Supplement Edition, and
If Life-Cycle Cost-Effective, exceed the standard by 30% (Btu Consumption, not Cost) Space Heating Space Cooling Domestic Hot Water Heating
If not LCC-effective, achieve maximum level of energy efficiency that is LCC-effective
Limitations in 10 CFR 435/IECC
Neglects Lighting & Appliance Loads
Simulated Performance: Must use same fuel type in baseline as design Heating Oil: 140,000 Btu/gal Propane: 91,800 Btu/gal Different Efficiencies Available in NG,
Propane, & Heating Oil Furnaces
Evaluation of IHS Staff Quarters
Simulated the energy performance for a 3-bedroom staff quarters unit at Fort Belknap
Modified the design to meet the IECC Baseline (Standard Reference Design)
Compared design to Baseline
Simulated Design Alternatives to Seek 30% Improvement
Applicability throughout IHS
Ft. Belknap – Climate Zone 6B Similar IECC Requirements also in Regions 7 & 8 Long Heating Season Short Cooling Season Dry Climate (Cold, Sunny Winter Days)
Does not compare well with Marine Climates, the Southwest, Southeast, or East Coast
U.S. Climate Zones
Energy Costs
Recent Post-Occupancy Evaluation (Southwest) Findings: Primary concern of Occupants: Energy Cost In some cases, monthly heating bills reached
a significant percentage of the rental rate Questions regarding unit sizing, placement of
heating registers, design & construction quality How does energy savings translate to cost
savings?
Life Cycle Cost Analysis
Examines energy cost savings versus first costs.
25-year analysis, comparing all proposed design modifications.
Follows federal standards for LCCA OMB discount rates Calculates Savings-to-Investment Ratio Calculates Discounted Payback Period Evaluates Internal Rate of Return
Case Study
Fort Belknap, MT
8952 Heating Degree Days198 Cooling Degree Days
Case Study
1525 SF (Gross) 12,200 CF (Conditioned Space) Crawlspace Foundation (Conditioned), with
ICF Walls Uninsulated Floor 2 x 6 Frame Walls with R-19 Cavity Insulation Windows: Aluminum Frame, Double-Paned,
10% of Conditioned Floor Area; (U = 0.46, SHGC = 0.45)
Design of Ft. Belknap Unit (3 BR)
Doors: Steel, Urethane Core with Thermal Break (R = 4.4)
Ceiling: R-49 Blanket Insulation Heating: Natural Gas Furnace, AFUE = 0.92 Air Conditioning: Conventional, SEER = 13 Hot Water: 50-gallon tank, NG heated Ducting: In conditioned crawlspace, return
ducting in conditioned space, no insulation Infiltration: SLA = 0.00048 ft2/ft2
Design of Ft. Belknap Unit (3 BR)
Results—Energy ConsumptionUsing Conventional Furnace
Results—Energy ConsumptionUsing Ground Source Heat Pump
Comparison of Heating/Cooling Systems
0 20 40 60 80 100
Baseline Building
Design Building
Use Vinyl Windows
Use Tankless WaterHeater
Double-InsulateCrawlspace Walls
Increase SHGC inWindows
Re-orient Windows
Apply Exterior Shading
Annual Energy Consumption, MMBtu
Conventional Furnace Ground Source Heat Pump
Evaluation of Energy Costs
Prices Vary Significantly By Region
Fort Belknap Block Charges –
Electricity: $0.0955/kWh
Natural Gas: $10.1187/MMBtu ($101.187/Therm)
Summary of Energy Costs Using Conventional Furnace
Savings = $200-$400/yearNot Addressed by10 CFR 435 (~30%)
Lighting & Appliances
Not addressed by 10 CFR 435
Constitutes ~25% of the total energy cost
A 40% savings in L&A = 10% savings in total energy cost
Energy Star Appliances: ~$75/yr savings (based on a $2000/yr energy budget)
Summary of Energy Costs Using Ground Source Heat Pump
Savings = $400-$550/year
Furnace vs. Ground Source Heat Pump
0%
10%
20%
30%
40%
50%
60%
70%
80%
Energy Savings Cost Savings
Furnace Ground Source Heat Pump
Energy Savings vs. Life Cycle Cost Savings
Comparison of Energy andLife Cycle Cost Savings
0.0%
5.0%
10.0%
15.0%
20.0%
25.0%
30.0%
35.0%
40.0%
1. 2. 3. 4. 5. 6. 7. 8.
Design Option
En
erg
y S
av
ing
s
0.0%
0.5%
1.0%
1.5%
2.0%
2.5%
3.0%
3.5%
4.0%
LC
C S
av
ing
s
Energy Reduction LCC Savings
Life Cycle Cost Analysis – Conventional Furnace
First Costs3 Bedroom Unit: $275,000Vinyl Windows: $(1,600)Tankless Hot Water Heater: $1,700
Life Cycle Cost Analysis – Ground Source Heat Pump
Each has a point of diminishing returns Conventional Furnace System:
Difficult to exceed 30% over IECC
More pronounced for LCC Savings Vinyl Windows have a
significant LCC benefit Remaining Iterations: Energy
Savings essentially “offset” first costs
0.0%
5.0%
10.0%
15.0%
20.0%
25.0%
30.0%
35.0%
40.0%
1. 2. 3. 4. 5. 6. 7. 8.
Design Option
Ene
rgy
Savi
ngs
0.0%
0.5%
1.0%
1.5%
2.0%
2.5%
3.0%
3.5%
4.0%
LCC
Sav
ings
Energy Savings vs. LCC Savings
LCCA – Conventional vs. GSHP
Energy Savings does not translate equally to cost savings
GSHP Swaps Natural Gas ($10/MMBtu) for Electricity ($28/MMBtu)
Higher First Cost for a GSHP
Infiltration
Infiltration
Baseline Model: 39% of total Heating Load
Final Model: 55% of total Heating Load
Diminishing Returns
A Closer Look at Infiltration
IECC Baseline(SLA=0.00048)
0.5 ACH(Structural
Insulated Panels) Δ %
Heating 43.4 42.8 0.6 1.4%
Cooling 2.7 2.6 0.1 3.7%
DHW 16.2 16.2 0 0%
Total 62.3 61.6 0.7 1.1%
A Comparison of Conventional Infiltration versus SIP Infiltration
Recommended Prescriptive Design Requirements:
Parameter Value
Basement Type Conditioned Crawl Space or Basement
Foundation Walls Insulated Concrete Forms, R-44 or greater
Above-Grade Walls 2x6 wood frame with R-19 cavity insulation; Investigate Feasibility of SIPs
WindowsVinyl Frame with Double-Pane (U=0.30 or below)Solar Heat Gain Coefficient = 0.60 or above
Doors Steel-urethane core with break (R=4.4 or greater)
Ceiling R-49 Continuous
Heating Natural Gas Furnace, AFUE=92% or greater
Air Conditioning SEER=13 or greater
Hot Water HeatingRequire tankless or solar as an option (emerging federal standards require that a
minimum of 30% of hot water be heated with solar heat)
DuctingIn conditioned crawlspace, Return ducting in conditioned space, Insulation not
necessary.
Infiltration Tested in accordance with ASHRAE 119, Section 5.1.
What Can Users Do?
Thermostat Settings Every °F = ~$30 savings/yr
Turn off Lights Turn down heat or A/C while away Choose a smaller unit (if available) Solar Shading (summer) Solar Gains (winter)
Recap
Federal Regulations Energy Savings in IHS Staff Quarters Computer Modeling of “Typical” Unit Best Measures for Saving Energy Impact on Utility Bills Life Cycle Cost Implications Recommended Design Modifications Energy Saving Practices (Occupants)
Conclusion
Identify Greatest Energy Sinks Which Ones Can We Address? Regional Impacts Energy Studies will be posted on DES
website (www.des.ihs.gov)
Questions
Top Related