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HomeMy WebLinkAbout1/8/2019 Item 5, EwanTiny House on Wheels Energy Usage Comparison December 2, 2018 Update San Luis Obispo City Council San Luis Obispo, CA Re: Tiny House on Wheels Energy Usage Council Members, This analysis of structural energy usage is provided in support of our City’s goal of attaining Net Zero by demonstrating and comparing the energy usage of a THOW built to ANSI standards (as per city ordinance). The tables below illustrate the energy usage of under insulated vs. insulated structures used for residential purposes. For this analysis Option #3 as illustrated by the City in their presentation to council was used (not too big, not too small) as the structure being modeled. California Energy Commission authorized modeling software was employed to create the computer models whose results are illustrated. The California Energy Commission requires that all residential structures, whether new, altered or added onto, meet compliance standards. There are not exemptions for size – i.e. a 20 square foot addition requires the developer to show compliance with the energy standards. Except for the ”T-24 Compliance” model, all structures use standard 2 x 4 wall & 2 x 6 floor/roof construction. The “All Electric” model is based on electric space and water heating – which is allowed under the ANSI standards (as is Fuel Oil also). The other models use gas fired tankless water heaters and small Direct Vent gas space heaters, commonly found in small homes. Please note – the first 2 information rows “Space Heating & Cooling” are the major energy use factors being compared. Column 05 is the CEC T-24 standard residential energy budget. Column 06 is the energy use for the modeled structure. Table # 1 – THOW CEC T-24 Compliance Achieved. This illustrates the energy usage allowed in a 2016 compliance residential construction. Space heating and DHW is gas. The energy required to heat this structure is ~ 1.5 times the allowed CEC heating budget. Table # 2 – THOW Esave. This illustrates energy usage with basic insulation you would find in a circa 1980-1990 residence. R-13 walls, R-19 Floor and Ceiling. Space heating and DHW is gas. The energy required to heat this structure is ~ 7 times the allowed CEC heating budget. Table # 3 – THOW ANSI Base. This illustrates the energy usage with insulation to ANSI Standards. Space heating and DHW is gas. The energy required to heat this structure is ~ 12.5 times the allowed CEC heating budget. Table # 3 – THOW ANSI Electric. This illustrates the energy usage with insulation to ANSI Standards w electric space heat and DHW. The energy required to heat this structure is ~ 9 times allowed “all electric” budget and ~29 times the standard budget. Observations: The State of California has actively promoted energy efficiency for the built environment since 1978 through Title 24, part 6. Title 24 has been updated over the years to set the stage for our “net zero” built environment, with the 2019 update fully embracing GHG reduction and promoting strategies to achieve net zero homes. California’s energy standards are crucial to reducing GHG (Green House Gas) emissions of the electricity and natural gas sectors, and to lowering the costs of energy to consumers. The proposed 2019 Energy Code will require a new residential structure to meet building efficiency standards separate from the new mandatory PV standard. IE: A new residential structure cannot rely on renewable energy to offset efficiency deficiencies of the envelope. The ”Tiny House on Wheels” modeled for this analysis, at 288 sq. ft., would be a substantial addition to an “Affordable by Design” home. As a structure built on the ground, it would absolutely have to meet State Energy Standards. The addition of this energy load to a residential property is neither small nor benign. During the load analysis and specification process for a Net Zero home, it is the small “phantom” loads that must be accounted for. Everyday appliances such as phone chargers, Wi Fi routers, DVR’s etc. appear to be negligible energy loads in the home. When these same loads are added up and multiplied by the hours and days of usage, these “benign” electronics become major energy drains. (A DVR may use as much energy as a refrigerator over the course of a year). Conclusion: Similar to CEQA requirements, the City may want to cite over-riding considerations and allow for energy use beyond the CEC standards. As with CEQA – the City needs to understand exactly what is being allowed by the proposed ordinance and the impact of that allowance. The least costly energy for the consumer and our environment is the energy never needed. Thank you John Ewan T-24 Residential Energy Analyst Net Zero SME San Luis Obispo, CA I am happy to model alternate designs if desired. Documentation is attached.