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Finding Residential Energy Solutions through Energy Modeling

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Presentation on theme: "Finding Residential Energy Solutions through Energy Modeling"— Presentation transcript:

1 Finding Residential Energy Solutions through Energy Modeling
A Case Study of Fort Belknap IHS Staff Quarters, Ft. Belknap MT I have been studying residential energy modeling for some time now Focus: Staff Quarters Energy Use (how to save energy & bills) I will be presenting a lot of numbers, which can be hard to communicate effectively- Engineers are known for not being the best communicators Introverted Engineer vs. Extroverted Engineer Michael R. Young, P.E. Civil Engineer Division of Engineering Services - Seattle Indian Health Service

2 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. Emphasis: to identify the most cost-effective ways to save energy in existing staff quarters

3 Overview Federal Regulations Case Study: Fort Belknap, MT Results:
Energy Consumption Annual Utility Bills Life Cycle Cost Analysis Recommendations: Design Here is an overview of my presentation:

4 Emerging Energy Regulations
EPAct 2005 (Public Law ) Federal Leadership in High Performance and Sustainable Buildings MOU EISA 2007 Executive Order 13423 Strengthening Federal Environmental, Energy, and Transportation Management 10 CFR 433, 434, 435 Executive Order 13514 Federal Leadership in Environmental, Energy, and Economic Performance EPAct: 2% Reduction in energy consumption in federal buildings every year (20% improvement by 2015) + metering requirements + 30% over ASHRAE 90.1 in new buildings MOU: Sustainability became a requirement (Green Buildings; “Guiding Principles”) EISA: Energy Independence and Security Act of 2007; more stringent energy performance goals: Fossil Fuel reduction to 55% by FY 2010, 100% by 2030 EO 13423: Each agency must reduce energy consumption in federal 3% annually, or 30% by FY 2015 CFR: Energy standards for Federal Residential Buildings (topic of this study) EO 13514: Net-zero energy by 2030.

5 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 10 CFR 435 has the most specific application to staff quarters

6 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 L&A: ~25-30% of all energy consumed

7 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 The effort to comply with these regulations has led to this study. We chose Ft. Belknap because the design is complete, and current.

8 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 Before I go on, first I need to point out the limited applicability nationwide: Heating Degree Days/Cooling Degree Hours for Ft. Belknap: 8952/4762 Page: 4349/6405 Phoenix: 1444/54404 Ponca City: 4285/24265 Seattle: 5122/1050

9 U.S. Climate Zones

10 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? Virtually nobody is happy about the utility bills they pay, so we have to take complaints with a grain of salt. However, there may be some real issues out there. For example, a recent POE showed-

11 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 Another aspect of this study is the LCC (condition given in the CFR)

12 Case Study Fort Belknap, MT 8952 Heating Degree Days
198 Cooling Degree Days Here is a quick background to our case study-

13 Case Study

14 Design of Ft. Belknap Unit (3 BR)
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) Here are the relevant design features of our new staff quarters in Ft. Belknap (here is an actual photograph of our first unit at the final inspection)

15 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 = ft2/ft2 SEER: Season Energy Efficiency Ratio

16 Results—Energy Consumption Using Conventional Furnace
After simulating the energy performance “as designed”, I modified it for design iterations:

17 Results—Energy Consumption Using Ground Source Heat Pump
Since there has been a lot of talk about ground source heat pumps lately, I ran the same simulations, only replacing the furnace with a GSHP. 9 100’ deep (model default) Loop flow: 9 gpm COP: 3.1 EER: 14.5

18 Comparison of Heating/Cooling Systems
This graph incorporates all the design iterations using both heating systems

19 Evaluation of Energy Costs
Prices Vary Significantly By Region Fort Belknap Block Charges – Electricity: $0.0955/kWh Natural Gas: $ /MMBtu ($ /Therm) Next, we looked at the impacts of these design modifications to the energy costs But first, a qualifier-

20 Summary of Energy Costs Using Conventional Furnace
Savings = $200-$400/year Not Addressed by 10 CFR 435 (~30%)

21 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) On the topic of lighting & appliances, this is something a facility manager can bring to the occupant

22 Summary of Energy Costs Using Ground Source Heat Pump
Next, I’d like to talk about the potential cost savings with these design iterations combined with a ground source heat pump Savings = $400-$550/year

23 Furnace vs. Ground Source Heat Pump
So now, how does the GSHP compare to a furnace in terms of cost? Although you are using much less energy, you are also swapping a cheaper fuel (NG) for a more expensive fuel (electricity) NG: $10/MMBtu Electricity: $28/MMBtu

24 Energy Savings vs. Life Cycle Cost Savings
Now, let’s compare the progression of each model run in terms of: Energy reduction Life Cycle Cost Savings

25 Life Cycle Cost Analysis – Conventional Furnace
Costs used in this analysis: Design (Higher Eff. Furnace, Less Glazing, add’l insulation, etc.): $1690 Replace Al with Vinyl: ($1600) Tankless Hot Water: $1700 Double Insulation on Crawlspace Walls: $1000 Remove Low-e Coating: ($200) Re-Orient Building: $0 Exterior Shading: $800 First Costs 3 Bedroom Unit: $275,000 Vinyl Windows: $(1,600) Tankless Hot Water Heater: $1,700

26 Life Cycle Cost Analysis – Ground Source Heat Pump

27 Energy Savings vs. LCC Savings
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 Now, a quick discussion about this graph-

28 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 Now, a quick discussion about the LCC comparison between furnaces and GSHPs-

29 Infiltration I’d like to bring up infiltration to this discussion, because the study did not address it. However, the model gives us some very startling results-

30 Infiltration Baseline Model: 39% of total Heating Load
Final Model: 55% of total Heating Load Diminishing Returns Here’s another statistic-

31 A Closer Look at Infiltration
A Comparison of Conventional Infiltration versus SIP Infiltration IECC Baseline (SLA= ) 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 0% Total 62.3 61.6 0.7 1.1% Oak Ridge National Laboratories conducted a study in which SIPs outperformed conventional stick-built construction by a factor of 15 to 1.

32 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 Windows Vinyl 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 Heating Require tankless or solar as an option (emerging federal standards require that a minimum of 30% of hot water be heated with solar heat) Ducting In conditioned crawlspace, Return ducting in conditioned space, Insulation not necessary. Infiltration Tested in accordance with ASHRAE 119, Section 5.1. The product of this analysis is the following table of recommended prescriptive design requirements.

33 What Can Users Do? Thermostat Settings Turn off Lights
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)

34 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)

35 Conclusion Identify Greatest Energy Sinks Which Ones Can We Address?
Regional Impacts Energy Studies will be posted on DES website ( In conclusion, I hope you can take away more information to enable you to-

36 Questions

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