Energy and the Built Environment

Transcription

1 Energy and the Built Environment Atila Novoselac Wesley Cole Energy Technology & Policy 10/23/12

2 Lecture Objectives How much energy is consumed in buildings How the energy is consumed How to make them better energy efficiency thermal comfort indoor air quality

3 Total Primary Energy Consumption in U.S. by Sectors Total primary energy: 97.3 x Btu (for 2011) Building energy costs $350 billion/year $0.031/kWh Source: EIA (2008)

4 Energy Principles: Site Energy vs. Primary Energy Primary Energy Site (End-use) energy is the energy directly consumed by end users Light Primary energy is site energy plus the energy consumed in the production and delivery of energy products Fresh air Thermal HVAC System HVAC Heating, Ventilation and Air-Conditioning Site energy (End use) Site Energy Primary Energy Distribution Storage Generation

5 Energy Consumption Monthly Profile for 100,000 sf Commercial Building in Austin ~12% ~96 MWh

6 Comparison of Energy for Heating and Cooling How to compare heating energy from gas and electric energy for cooling? 1) Convert all to primary energy 2) Convert end use energy from gas to electric energy you would get from this gas You will need: - Conversion factors: 1000 BTU = KWh, 1,000,000J=0.278 KWh - Average efficiency of electric generation systems: 33%

7 Same Building in Minneapolis, Minnesota ~150% ~845 MWh NOTE: We would never build the same buildings in Austin and Minneapolis

8 An Average Commercial Building in US HVAC ~ 35%

9 Analysis of Energy Consumption in Residential Buildings We are considering a model building used in Austin Energy analyses Model house: - Location in Austin -2300sf -R13 walls -R30 attic -4 occupants -Surface absorptivity to Solar rad.: 0.7 -Typical (average) internal loads -Infiltration/Ventilation 0.5 ACH - Double glazed widows - Glazing are 20% south, 25 north, 5% east and west - SHGC=0.54 (reflective bronze - glass)

10 Energy Consumption in Newer Residential House in Austin Miscellaneous Cooling ~45% Washer Range Refrigerator Year: 2000 (15,600 kwh) Including gas Lighting Dryer Hot water Heating End use energy where energy from gas is converted to equivalent electric energy

11 Energy Consumption and Improvements in Code Requirements kwh Miscellaneous Washers Range kwh kwh Desired Value! Refrigerator Lighting Dryer Hot water Heating Cooling kwh target (2015)

12 Energy Consumption: kwh/year (to get approximate cost multiply by ~0.1) Units are in kw/h per year Example question: A window company is offering you a better windows (SHGC=0.27) and that cost $10,000. Is it worth while?

13 What Drives Energy Consumption? Consider 2300 ft 2 home in Austin 30% cooling, 14% heating, 12% hot water, and 44% lighting, appliances, and other devices Cooling Energy Total Energy Year-Round Energy Internal Loads 36% 11% 2.3% Radiation (windows) 23% 7% 19% Radiation (ext. surfaces) 11% 3.5% Combined Radiation Infiltration 7% 2.2% 5.5% Conduction 23% 7% 17%

14 Type of lamps Incandescent Fluorescent and HID LED. Type Lighting in Buildings Relative comparison power consumption for the same light output Lifetime Incandescent 40 W 2 8 months Fluorescent and HID W 1 2 years LED 3-10 W (or not?) 10+ years

15 Appliances Contribute significantly to energy consumption (especially in residential buildings)

16 Washer Comparison 470 kwh/yr ($50/yr) Cost: $ kwh/yr ($15/yr) Cost: $403 Source: Home Depot (2012)

17 Building Envelope HVAC Major question: How much ventilation, how much heating, and how much cooling we need to have to provide satisfactory air quality and thermal comfort in the building?

18 Building HVAC Systems (Primary and Secondary Building Systems) AHU Air Handling Unit Fresh air For ventilation AHU Distribution systems Primary systems Air transport Electricity Cooling (chiller) Heating (boilers) Building envelope Secondary systems (or Gas) Gas HVAC systems affect the energy efficiency of the building as much as the building envelope

19 How to make a zero energy house? Turn off electric power and gas Environmental parameters need to be defined by - thermal comfort and - indoor air quality

20 Thermal Comfort Combination of - Indoor environmental factors - Personal factors Human body - in thermal equilibrium with the environment

21 Thermal Comfort Equation Energy balance for human body Metabolic Heat - Work = Energy that body release

22 Thermal comfort Metabolism health condition and activity Clothing level Air Temperature Mean Radiant Temperature Air Velocity Humidity P.O. Fanger PPD Predicted Percentage of Dissatisfied Scale 5-100%

23 Thermal Comfort Factors that we Control in Buildings Air Temperature Humidity Air velocity Surrounding Temperature Air temperature, relative humidity and velocity are defined by ASHRAE standard 55: Thermal Environmental Conditions for Human Occupancy.

24 Indoor Air Quality (IAQ) Americans are Indoor Creatures Indoors 89% 2/3 of time in home Transit 6% Outdoors 5% 18 hours indoors for every 1 outdoors

25 USEPA Risk Rankings 1. (tie) Worker exposure to chemicals 1. (tie) Indoor radon 3. Pesticide residue on foods 4. (tie) Indoor air pollutants (non-radon) 4. (tie) Consumer exposure to chemicals (includes cleaning fluids, etc.) 6. Hazardous/toxic air pollutants 7. Depletion of stratospheric ozone 8. Hazardous waste sites (inactive) 9. Drinking water (radon and THMs) 10. Application of pesticides 16 others.. (including groundwater contamination at 21, criteria air pollutants at 22, etc.)

26 Billion kg/year Exposure in Buildings Chemicals Global Production: Synthetic Organic Chemicals Wall-to-wall carpet Cleaners Air fresheners Pesticides Personal care products Building materials Moisture related pollutants Outdoor pollutants (O3, PM 2.5, ) Year Challenges: Very difficult to detect/measure them Even more difficult to quantify consequences

27 Prevention Remove sources Exposure Reduction Use low emission materials Keep your house dry Many trivial measures such as: take off your shoes in homes. Dilution Ventilation Filtration Ventilation rate is defined by ASHRAE Standard 62: Ventilation for Acceptable Indoor Air. Quality Don t seal your homes!

28 LEED - Leadership in Energy and Environmental Design Effort to integrate sustainability into building industry It promotes sustainable building and development practices through a suite of rating systems that recognize projects that implement strategies for better environmental and health performance

29 LEED Affects: Sustainable Sites Water Efficiency Energy & Atmosphere Materials & Resources Indoor Environmental Quality Locations & Linkages Awareness & Education Innovation in Design Regional Priority

30 LEED Certification is a Rating System USGBC established four levels of LEED that Evaluates: Sustainable Site Water Efficiency Energy & Atmosphere Materials & Resources Indoor Environmental Quality Locations & Linkages Awareness & Education Innovation in Design Regional Priority

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32 Note that Energy and Indoor Environmental Quality (IEQ) count for 50 points out of 110. ( Silver Certification) However, how do we consider different quantities? increases energy use but improves indoor air quality Ventilation, Air cleaning reduces exposure to some compounds and increases exposure to other compounds Low-VOC paint, Ventilation improves exterior environment and degrades indoor environment Fly-ash concrete, Green roofs

33 LEED is far from perfect! It has many positive sides, but negative too Current problem with LEED: An average LEED building is more efficient, but 28 35% of LEED buildings use more energy than their conventional counterparts LEED is still developing Every version gets better

34 Net-Zero Building (RSF) eractive.html