ARCH403_SemesterReview(1).pdf

Environment & Building Systems I Semester Review Image from Thermodynamics and Everyday Life, Javier Garcia-German, 2018 ARCH 403 Final Exam Date December 6th 8 AM (30% of the final score) / Open Notes (No page limitations / do not open lecture slides) Content Included in the Final Exam • Environ...

Environment & Building Systems I Semester Review Image from Thermodynamics and Everyday Life, Javier Garcia-German, 2018 ARCH 403 Final Exam Date December 6th 8 AM (30% of the final score) / Open Notes (No page limitations / do not open lecture slides) Content Included in the Final Exam • Environmental Impact • Thermodynamics • Human Comfort: Thermal Comfort • Passive Solar Design: Solar Basic + Shading Design + Solar Carving / Heating • Daylight • Passive Cooling Design • Building Energy Load Calculation • Life Cycle Analysis • Introduction of HVAC • Introduction of Renewable Building Energy Systems Question Types: T/F, single choice, multiple choices, calculation, drawing, and short answer What is HEAT? The movement of atoms and molecules within a substance Large Density Relatively Heavy Small Density Relatively Light UNIT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! HEAT (THERMAL ENERGY) : A form of energy transfer between systems ( or bodies) : The amount (quantity) of “thermal” energy exchanged due to a temperature difference : Unit SI Metric: Joule (J) US Metric: British Thermal Units (BTU) ex) The amount of heat required to raise the temperature of one gram of water from 50 F to 55 F *Wh (watt hour) & kWh (kilowatt hour) also represent the amount of energy. 1Wh = 3,600J UNIT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! POWER : The rate at which work is done, or energy is transmitted : The amount of energy transferred or converted per unit time : Unit – Watt (W) = Joule / second or Btu / second (1 Watt = 1 Joule / sec) ex) Device A = 100 J / 10 sec = 10 Watt Device B = 100 J / 5 sec = 20 Watt HEAT FLUX : Heat Flux q” = The flow of heat energy through a defined area over a defined time = Joules (energy) / area (m²) * time (seconds) = Joules / (m² *sec) : 1 Watt (W) = 1 Joule / sec, therefore q” = Joules / (m²*sec) = Watt / m² = W / m² Barcelona Cathedral CONDUCTION : HIGH THERMAL MASS CONVECTION : BUOYANCY EFFECT RADIATION HEAT EXCHANGE Thermal Conduction Related Building Performance Values R-Value A measure of a material’s ability to impede heat flow ( a higher R means less heat flow) *R-Value is cumulative. U-Value A measure of the ability of an assembly to conduct heat (a higher U-Factor means more heat flow) Specific Heat Capacity The amount of heat required to raise the temperature of a substance by one unit -> Related to the ability to store heat within a substance! = Thickness (m) Thermal conductivity (W/m*K) Three Indoor Temperatures! Dry-bulb air temperature : Air temperature measured by a dry-bulb thermometer : Typical air temperature Mean radiant temperature Temperature based on the principle of the net exchange of radiant energy between a human and their surrounding environment. Operative temperature: When designing heating and cooling systems, operative temperature is generally used. Dry-bulb Temperature + Mean Radiant Temperature 2 Unique Outdoor Temperature for the Outdoor Comfort Analysis Universal Thermal Climate Index (UTCI) : An equivalent temperature in degree Celsius incorporating the assessment of the thermophysiological effects of the atmospheric environment. U.S. Climate Zone Two U.S. Building Standards! 1) ASHRAE 90.1 ASHRAE 90.1 Standard for Building Envelope and Mechanical Systems How to Read the Standard for the Minimum R-Value Requirements for Building Envelops C.I = Continuous Insulation Two U.S. Building Standards! 2) ASHRE 55 Thermal comfort is determined by the combination of … Individual factors Activity (Metabolic Rate) Clothing (Clothing Insulation) Environmental factors Air temperature (F or C) Relative humidity (RH) Air movement (ft/min or m/s) Mean Radiant Temperature (F or C) ASHRAE 55 Standard Psychrometric Chart! Dew point temperature!! Wet bulb temperature!! Sun Path Diagram Altitude: Solar elevation angle describing how high the sun appears in the sky Altitude angle describes height of the sun in the sky - Varies with month and time of day Altitude lines are represented as concentric circular Dotted lines that run from center out, in 10 increments From 90 to 0 Sun Path Diagram Azimuth: Horizontal angle measured clockwise from a reference direction, typically North, to a point or object in the sky or on the Earth’s surface. Azimuth angle varies with month, and time of day; range is most “extensive” in summer. Azimuth lines run around the edge of the diagram in 15 Increments. Shading Design Principles An overhang (or horizontal louver) is an “altitude-responsive” device A fin (or vertical louver) is an “azimuth-responsive” device Passive Solar Heating The Three Main Types of Passive Solar Space Heating Systems 1. Direct Gain 2. Trombe Wall 3. Sunspace Blue Ridge Parkway Visitor Center (2008) Units for Daylight!!!!!! Glare 9:00 12:00 15:00 DGP=0.28 DGP=0.38 DGP=0.41 Daylight Glare Probability (DGP) Brightness of Glare Source (Luminance) Size of Glare Source MAR 21 Overall Light Level In Room (Illuminance) Position of Viewer’s Eye DGP=0.31 DGP=0.32 DGP=0.47 DGP=0.19 DGP=0.30 DGP=0.31 JUN 21 DEC 21 Complex Calculation DGP 0% ~ 100% Passive Cooling Natural Ventilation Lanchester Library, UK Evaporative Cooling Laurel Village Pavilion, Colorado Radiative Sky Cooling Air Flow: Fundamental How does air flow? Natural convection currents Buoyancy effect Differences in pressure Proper Aperture Locations to Accelerate Natural Ventilation Size of Apertures for Cross-Ventilation Size of Openings for Cross-Ventilation Inlets and outlets should be the same size, If they cannot be the same size, the inlet should be smaller to maximize the velocity Ventilation Principle for Cooling: Tower Application Combination of Bernoulli Effect & Buoyancy Effect (Lift & Stack Effect) Solar Chimney VS Evaporative Cooling Tower Solar Chimney Buoyancy effect High-conductive material is ideal Evaporative Cooling Tower Down drift Less-conductive material or thermal mass is ideal Indirect Evaporative Cooling: Roof Pond Exploded House by GAD Architecture Bodrum, Turkey Building Heat & Cooling Load Calculation Basic Heat Gain Q1 Q2 Heat Loss or T1 T2 ` The Unit of Energy ‘Q’ = Joule (J) or Watt.Hour (Wh) For instance, if 10,000J of energy is added to the room, and the room temperature, originally at 78F, is increased to 86F. The room is equipped with a 100W air-conditioning system. How long will it take to cool the room back to 78F? Building Heat & Cooling Load Calculation Basic Heat Gain Q1 Q2 Heat Loss or T1 T2 ` The Unit of Energy ‘Q’ = Joule (J) or Watt.Hour (Wh) For instance, if 10,000J of energy is added to the room, and the room temperature, originally at 78F, is increased to 86F. The room is equipped with a 100W air-conditioning system. How long will it take to cool the room back to 78F? 100 seconds 10,000J / 100W(=100J/s) = 100 seconds Outside Building Surface Heat Balance Heat transfer between the sun and wall Short Wave Radiative Heat Transfer (Gain only) Heat exchange with the air and surroundings Long Wave Radiative Heat Exchange (Gain or Loss) Heat exchange driven by wind Convective Heat Exchange (Gain or Loss) Conductive heat into the wall (Gain or Loss) Inside Building Surface Heat Balance qsol & qsw Shortwave radiative heat gain from the sun (through windows) and lighting (Gain only) Longwave radiative heat gain from equipment (Gain only) qlw Heat exchange between interior surfaces (mainly walls) Longwave radiative heat exchange (Gain or Loss) Heat exchange with interior air qconv Convective heat exchange (Gain or Loss) qsol + qsw + qlw + qlwx + qconv= -qki (+) (+) (+) (+ or -) (+ or -) (+ or -) qlwx Why Energy Load Calculation Important? 1. To Design Heating and Cooling Systems Peak Cooling Load Peak Heating / Cooling Load Calculation (The amount of heat loss/gain to/from the outdoor environment at design conditions, which must be made up/removed by mechanical systems to maintain indoor comfort) & Average Heating / Cooling Load Calculation Optimal Mechanical System Size Design Why Energy Load Calculation Important? 2. For Architectural Design Energy Load Characterization Monthly Load Use Reduce solar gains with external shading (See page 4.) kWh Fans & Pumps Equipment Lighting Cooling Heating DHW 18000 16000 Reduce lighting Energy consumption ELI 14000 12000 10000 8000 6000 Reduce overheating with outdoor air & apply natural ventilation 4000 2000 0 Jan Improve Envelope Values (See Page 4.) Reduce domestic hot Water heating energy with Solar collectors Feb MONTHLY Mar Apr May Jun Jul Aug Sep Oct Nov Dec HVAC Basic The objective of HVAC Control the indoor air temperature Moisture control Filtration of air & containment of airborne particles Supply of outside fresh air for control of oxygen and carbon dioxide levels Air movement control Components of HVAC Distributor + + Heating component (ex. Boiler) + Cooling component (ex. Chiller) Air Handling Unit + Refrigerator + Supplemental system (cooling tower) Air Handling Unit (AHU): The Heart of Air-Based Systems Function of AHU 1) Air temperature control (Coils) 2) Moisture control (Humidifier & Dehumidifier) 3) Air distribution (Fan & damper) 4) Fresh air handling (Filters) 5) Air mix (Heat recovery) *Depending on the types of AHU, all these features may be included as a whole, or certain parts may be included. Components of HVAC Distributor + + Heating component (ex. Boiler) + Cooling component (ex. Chiller) Air Handling Unit + Refrigerator + Supplemental system (cooling tower) Heating and Cooling Coils Installed in AHU are connected to a boiler and chiller, respectively, to provide heating and cooling. The chiller requires a refrigerator. Components of HVAC: Refrigerator Compressor Heated Gas Refrigerant Super Heated Gas Refrigerant Evaporator Condenser Hot Air Released Cool Air to Inside Indoor Ambient Air Subcooled Liquid Refrigerant Expansion Valve Refrigerant Circuit Outdoor Ambient Air Warm Liquid Refrigerant Components of HVAC: Evaporative Cooling Tower To Cool the CONDENSER of a refrigerator; therefore, better cooling performance Basic Types of Air-Conditioning Systems 1. Direct Expansion (DX) System: Cools AIR directly 2. Water-Chilled System: Cools WATER first or Cools WATER & AIR simultaneously 3. Roof Top Unit (RTU) System: Packaged Unit Water-Chilled System In case of the chilled water system the compressor, condenser, expansion valve, and chiller are all kept at the same level in the single plant room. The chilled water flows to various air handling units kept on different floors of the building ->No Height difference limitation Suitable for a large / multi-stories building due to its installation and maintenance benefits. Forced Air System Radiant System Regulating air directly Regulating surface temperature Benefits of Radiant Systems Over Air-Based Systems: Even Heat Distribution & Higher Comfort Level Benefits of Radiant Systems Over Air-Based Systems: Better Energy Efficiency Radiant Systems Ideal water temperature for heating: 80 - 100F Ideal supply air temperature for cooling: 55-65F + Less heat loss through ductwork and reduce Temperature stratification Air-Based Systems Ideal supply air temperature for heating: 100-120F Ideal supply air temperature for cooling: 55-60F Benefits of Radiant Systems Over Air-Based Systems: Design Flexibility Disadvantages of Radiant Systems Over Air-Based Systems: Maintanance Disadvantages of Radiant Systems Over Air-Based Systems: Difficult Controllability (inequivalent heat distribution potential) & Delayed Heat Transfer The Whole Life Carbon Assessment: Radiant System vs All-Air System Non-Residential Building Case The Whole Life Carbon Assessment: Radiant System vs All-Air System Non-Residential Building Case: Whole Life Carbon Emissions The percentage of embodied and operational carbon to whole life carbon Air-Based System: 71% and 29% Radiant System; 82% and 18% The Whole Life Carbon Assessment: Radiant System vs All-Air System Non-Residential Building Case: Whole Life Carbon Emissions The whole life carbon of the radiant system is approximately 10% lower than that of the air-based system. Solar Energy Wind Energy Geothermal Energy Geothermal Building Energy System = Geo Exchange, Earth-Coupled, Ground-Source, or Water-Source A geothermal system takes advantage of this by exchanging heat with the earth through a loop. 90°F Air Temp Heat Pump Water is circulated (Heat exchanger) 60°F Ground Temp (10’ below surface) 5°F Air Temp Heat Pump Water is circulated (Heat exchanger) 55°F Ground Temp (10’ below surface) Ground-Source Heat Pump / Air-Source Heat Pump Outdoor Air (45 F -> 35 F) Compressor (50 F -> 180 F) (50 F) Indoor (68 F -> 86 F) Ground Temp (60 F -> 35 F) (180 F) Compressor (75 F -> 180 F) (75 F) (180 F) (40 F) (120 F) Indoor (68 F -> 86 F) (60 F) (45 F) (68 F) (35 F) (40 F) (86 F) (35 F) (120 F) Air-Source Heat Pump Ground-Source Heat Pump The Urgent Need for Measurement and Reduction of Embodied Carbon Emissions However… Growing importance of embodied carbon as building operational energy decarbonizes Life Cycle Assessment Why & how do you conduct an LCA? The broad goal is to understand a building’s environmental impact, but it is helpful to identify a more specific goal. For instance, • Does the environmental impact of cross-country lumber transportation outweigh the environmental benefits of building a wood structure in this location? • What are the major contributors to Global Warming Potential in my building? • How many kilograms of carbon emissions can I save by increasing the substitute cementitious material in my concrete mix? • Which is less environmentally impactful: PIR foam insulation or XPS foam insulation? My sincere thanks to everyone for your hard work, patience, persistence, the numerous questions, active participation, and the fantastic class vibe this semester!