architecture energy 2011

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LOISOS + UBBELOHDE

ARCHITECTURE . ENERGY . 2011


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ARCHITECTURE . ENERGY . 2011


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architecture . energy . 2011

2011 Loisos + UbbelohdeMany illustrations, tables, and images contained in this book have been derived from textbooks, standards,guidelines, and the Internet. Copyright holders are noted by citation. All other information, images, and ideas inthis publication are the property of Loisos + Ubbelohde and are offered under a Creative Commons license thatallows others to copy, distribute, and display the copyrighted work only if the correct authorship is legible on theimage, and the image is used verbatim and for noncommercial purposes.

To order additional copies of this publication contact:Loisos + Ubbelohde1917 Clement Ave. Bldg 10aAlameda, California USA 94501T + 1 510 521 3800F + 1 510 521 3820E [email protected] www.coolshadow.com

Cover Image: Torsion by Jim Soliven, generated using Processing.


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acknowledgments

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It is with deep gratitude and respect that we would like to thank our partners in Tokyo and Berkeley:

Shuzo Murakami, Building Research InstituteMasao Koizumi, Tokyo Metropolitan UniversityKengo Kuma, Tokyo UniversityNobufusa Yoshizawa, Institute for Building Environment and Energy ConservationBalazs Bognar, Kuma and Associates

Dana Buntrock, UC BerkeleyDavid Fannon, UC BerkeleyKyle Konnis, UC BerkeleyJeremy Fisher, UC BerkeleyCenter for Japanese Studies, UC Berkeley

George Loisos Susan Ubbelohde Brendon Levitt Santosh Phillip Ibone Santiago Eduardo PintosPrincipal Principal Associate Associate Associate Associate

Loisos + Ubbelohde Staff for Workshop:


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3 Energy, Comfort and Cost

DAY ONE: LIGHT10 Daylight and Shade14 Tools and Software16 Resources and Rules of Thumb

DAY TWO: HEAT

20 Sun and Surface22 Thermal Mass24 Insulation26 Tools and Software28 Resources and Rules of Thumb

DAY THREE: AIR32 Ventilation34 Machines37 Tools and Software38 Resources and Rules of Thumb

DAY FOUR: ENERGY42 Renewable Energy44 Resources and Rules of Thumb46 Integrated Design

APPENDIX48 English-Japanese Dictionary50 Works Cited

contents


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Psychrometric-Bioclimatic Chart showing regions where architectural filters could potentially reduce energy use.

Psychrometric Chart with winter (left) and summer(right) comfort zones for Los Angeles.

Psychrometric Chart with average annual comfortzone and hourly data plotted.

5

This means that the surface temperature of the walls can actually haveas much of an influence on our thermal comfort as the temperatureof the air. A metric known as operative temperature is the averageof the air temperature and mean radiant temperature in a space.Operative temperature is often misunderstood or ignored by airconditioning specialists but it is crucial to an accurate understanding ofoccupant comfort.

To establish the operative temperature, humidity, and air speed (andthereby start to define occupant comfort), we can define the role ofthe building in filtering the ambient environment. There are only fivemethods by which heat can flow through the building envelope and

each is associated with a strategy for climatic mediation, or filter:

Filter Heat Flow / Storage Insulation Conduction Ventilation Convection Glass and Shade Radiation (light and heat) Evaporation / Dessication Latent Heat Thermal Mass Thermal Capacity

These filters or strategies for mediation can be combined to reject,accept, or store ambient energy. They are the fundamental paletteof the building envelope and the principal arena of design for the


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day one: light


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Daylight in a unilaterally lit room with window facing:(a) the sun, (b) overcast sky, (c) away from the sun.From Robbins 1986, 70.

Daylight in a bilaterally lit room on a: (a) clear dayand (b) overcast day. From Robbins 1986, 81.

Iso-illuminance plan of a daylit room rotated to face: (a) the sun,(b) 45, (c) 90, (d) 135, (e) 180. From Robbins 1986, 77.

resources and rules of thumb

Higher window head heights will light the ceiling more and allowdaylight deeper into a space.

Ceiling brightness has the biggest affect on desk illumination be-cause horizontal surfaces see primarily ceiling.

Sloping the ceiling away from the fenestration area will help in-crease the surface brightness of the ceiling further into a space.

Overcast skies are brighter than clear, north skies. Luminance contrast ratios greater than 20:1 in the visual field of

a daylighted space will likely result in glare. In electrically lightedspaces ratios of 10:1 are preferred.

In a room that is lit by a punched window on one side, the darkestsurface is the wall with the window and the brightest surface is theview out the window itself. Placing the window next to a perpen-

dicular wall or canting the wall next to the window jamb will helpthe eye transition.

Horizontal shading devices are more effective than vertical ones onsouth, east and west facades. To block all direct beam on an eastor west facade while still allowing daylight, requires an operableshade.

North facades will receive direct sun on summer mornings andafternoons. Vertical fins are effective for cutting this sun.

As a general rule, overhangs with a depth equal to one third or

one half the height of the window will provide some high sky glareprotection and some control for direct solar radiation.

The primary purpose of a light shelf is to reduce light levels closestto the window so that there is less contrast between perimeter andin-board spaces. The secondary purpose is to reflect light back uponto the ceiling. This reflection is most effective when the lightshelf can see the sun or very bright portions of the sky.

As a general rule of thumb, a skylight area about 5% of the floorarea is sufficient to daylight a space with good energy efficiency.For more visually intense spaces, such as art studios and for placeswith high latitudes and cloudy skies 10% is good.


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Books

Daylighting Performance and Design, 2nd Editionby Ander, G. D. New York: John Wiley & Sons Inc., May 2003.

Daylight Design of Buildingsby Nick Baker and Koen Steemers,London: James and James, 2002

Daylighting Performance of Buldings, edited by Marc Fontoynont. Brussels: James and James, 1999.

Light Revealing Architectureby Marietta Millet. New York: Van Nostrand Reinhold, 1996.

Daylighting: Design and Analysisby Robbins, Claude L. New York: Van Nostrand Reinhold Company, 1986.

Daylightingby Hopkinson, R. G., Petherbridge, P., and Longmore, J. London, England: University College, 1966.

Websites

Daylight in Buildings: A Source Book on Daylighting Systems and Components (gaia.lbl.gov/iea21)

Lawrence Berkeley Lab Daylighting Information (windows.lbl.gov/daylighting/Default.htm)

eLAD An eLearning platform for commercial building daylighting and lighting systems (elad.lbl.gov/index.php/Body_of_Knowledge)

Whole Building Design Guide (www.wbdg.org/resources/daylighting.php)

Autodesk Ecotect Analysis (www.autodesk.com): Weather Tool climate analysis software bundled with Ecotect

Climate Consultant (www.energy-design-tools.aud.ucla.edu): Climate analysis freeware

Radiance (radsite.lbl.gov/radiance): Main portal for Radiance software including freeware and tutorials

DIVA (www.diva-for-rhino.com): Radiance plug-in for Rhino

False color luminance rendering.Radiance rendering post-processed with human visual response algorithm.


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d t h t


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day two: heat


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thermal mass


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A stone cathedrals thermal mass dampens the ambient tempera-ture swings.

thermal mass

How does thermal mass store heat?Heat capacity is a material property that is a form of energy storage. Heat is transferred to the surface of a materialand is then conducted from the warmed surface to the cooler interior of the material. When the surface becomeswarmer than other objects in the room it radiates heat to them. Stored heat from the warmer interior is then con-ducted to the cooler surface. The time that this takes depends on the heat capacity of the material, the thicknessof the material, the surface area exposed to the room and the temperature difference between the room and thesurface. Materials such as concrete or stone are thermally massive because they have a high heat capacity whereaswood and plastic are not able to store heat for very long.

How does thermal mass keep people comfortable?Massive materials act as a thermal flywheel, dampening ex-tremes through absorption and emission. This typically hap-pens on a daily basis in climates with noticeable temperaturedifferences between day and night. As temperatures riseduring the day, the mass absorbs the heat keeping the spacecool. As temperatures decrease at night, the mass releasesthe stored heat keeping the space warmer than outside.

When designed properly, mass can be a thermal stabilizerfor a building.

Can thermal mass work on an annual cycle to balanceout winter cold and summer heat?In a space built of thick stone like a Gothic cathedral, thereis so much mass that the middle of the stone walls assumesthe average annual outside temperature. In the morning,sun begins to warm the outside surface of the stone butthe inside is still cool. By late afternoon, the stone has onlywarmed up slightly. During the evening it loses this heatthrough convection to the cool air and radiation to the nightsky. Like a large ship sailing on the open sea, any changesin core temperature happen very slowly. In a Mediterraneanclimate such as Italys, stone cathedrals remain relativelycomfortable all year long at 16C with no supplementaryenergy inputs. In England, however, where the average

annual temperature is 10C, the mass is a liability during thecold, damp winters.


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tools and software


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ASHRAE-55 comfort chart for conditioned buildings

ASHRAE-55 adaptive comfort chart for naturallyconditioned spaces.

tools and software

How to measure thermal comfort?There are four environmental variables that contribute to humancomfort. Each one can be measured with the following tools:

Air Temperature ThermometerHumidity HygrometerRadiant Temperature Infrared ThermometerAir Speed Anemometer

The thermometer and hygrometer require no specialized knowl-edge to use. Depending on the sensitivity of the meter, reactiontime can vary. By cupping the meter in your hand you can get agood idea how fast the meter reacts to humidity and temperaturechanges in the environment.

To use an infrared (IR) thermometer, point the device at the surfaceyou want to measure and pull the trigger until a temperature reg-

isters. Some IR thermometers allow you to select the emissivity ofthe surface and others default to =0.95, which is a common valuefor materials. Mean radiant temperature is a complex calculation,but taking an average of the walls, ceiling, and floor is a useful ap-proximation. Be sure to bias the calculation towards the surfacesthat are closer to you. Air speed measurements will be discussedon Day 3.

What do my measurements mean for comfort?

Typical comfort criteria used by mechanical engineers specifies thatfully mixed air should be between 18C and 22C, and between40% and 60% relative humidity. These criteria assume that therooms mean radiant temperature is the same as the air tempera-ture and that there is no discernable air movement.

More sophisticated comfort criteria specify an operative tempera-ture. Operative temperature is a weighted average between the

mean radiant temperature (MRT) and the air temperature. In lowmass buildings the MRT will be equal to the air temperature. Inhigh mass buildings you will see substantial differences.


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Common glass types organized by relationship between heat and light transmission


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29

BooksClimateskin: building-skin concepts that can do more with less energyby Gerhard Hausladen. Basel: Birkhauser, 2008Thermally active surfaces in architectureby Kiel Moe. New York : Princeton Architectural Press, 2010Double-skin facadesby E. Oesterle. Munich: Prestel, 2001

Solar control & shading devicesby Olgyay & Olgyay. Princeton : Princeton University Press, 1957WebsitesSolar Control Facades (gaia.lbl.gov/hpbf/techno_a.htm): technical information on glass and shadingDesigning with the Pilkington Sun Angle Calculator (www.sbse.org/resources/sac/PSAC_Manual.pdf)Thermal mass calculator, part of Material Database for Whole Building Energy Calculations (www.ornl.gov/sci/roofs+walls/AWT/Ref/sips.htm)ASHRAE Standard 55. Discussed in: A Better Way to Predict Comfort (www.cbe.berkeley.edu/research/pdf_files/OlesenBrager2004_comfort.pdf)WUFI (www.ornl.gov/sci/ees/etsd/btric/wufi.shtml)THERM (eetd.lbl.gov/eetd-software-therm.html)

HEED (www.energy-design-tools.aud.ucla.edu/heed)EnergyPlus Energy Simulation Software (apps1.eere.energy.gov/buildings/energyplus/)COMFEN (windows.lbl.gov/software/comfen/comfen.html)

Relationship of glazing to opaqueenvelope for insulation perfor-mance. Adapted from Brown2001, 47.

300mm concrete 0.17

1-pane glass,alum frame

0.14

2-pane glass,wood frame

0.36

2-pane, low-e, argon,wood frame

0.52

3-pane glass,wood frame

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25mm Fiberglass 0.62

25mm Aerogel 1.76

50x100 metal stud@ 400

1.24


1.47


1.63


1.98

50x150 wood stud@ 400

3.08

50x150 wood stud@ 600

3.33

50x100 metal stud@ 400 w/ 25mm ext rigid 2.11

50x100 metal stud@ 400 w/ 50mm ext rigid

2.82

R Value (SI) by Assembly


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day three: air


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day three: air

ventilation


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Wind tunnel test of a model in section and plan showing regions of positive andnegative pressure. From Olgyay 1963, 103.

What drives natural ventilation? Is it heat or wind?Air moves by pressure differences. These differences can be induced by wind or heat. As air cools it becomesdenser and sinks, displacing warmer air which, in turn, rises. Pressure-driven air movement is the result of a force(such as a fan or the wind) creating positive pressure on the windward side and negative pressure, or suction, onthe leeward side. Both of these mechanisms commonly take place in buildings, although some strategies rely onone method over the other. In either case, the architectural envelope can filter the ambient air to control ventila-tion rates.

Is ventilation for fresh air the same as for cooling?

Ventilation is the term used for both providing fresh air and providing cooler air to the interior. Air needs to beexhausted because CO

2accumulates in an occupied space. Codes (such as ASHRAE 62.2) require a minimum ven-

tilation rate that varies by building type. For most types, a barely perceptible ventilation rate of 7-9 L/s is required.As air is exhausted, either naturally or mechanically, fresh air must take its place and so there needs to be a clearpath for its entry into the building. When outside air is introduced for cooling, it replaces the interior air that haswarmed up and needs to be exhausted. This kind of ventilation for cooling can be driven by wind, heat or mechan-ically by fans. Whole-building fans use one-tenth the energy of mechanical air-conditioning systems.

How do ceiling fans cool if they dontprovide fresh air?Air moving across the skin causes localizedevaporation, which can have a cooling effectof 2-4C. This results in perceptible coolingeven though the air temperature in the roomhas not dropped. The cooler the air thatmoves across your skin, the faster the heatexchange can happen and the faster you will

feel cooled down. Ceiling fans use a smallpercentage of the energy used by mechanicalair-conditioning systems and are often helpfulin supplementing air conditioning for comfort.

How big should my window openings befor cross ventilation?Wind causes a positive pressure on the wind-

ward side and a negative pressure on theleeward side of buildings. To equalize pres-sure, fresh air will enter any windward open-


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machines


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Air-based systems require extreme air-supply (hot in winter, coldin summer) which consumes more energy and less comfortable.Adapted from Moe 2010, 76.

The fundamental components of a heating or cooling system.

heating mode

cooling mode

convection system radiant systemMachines, by which we mean mechanical systemsor HVAC (heating, ventilating and air conditioning)equipment, supply or extract energy to make a spacecomfortable. Because machines are expensive andtypically require energy from the grid, we see them asa supplement to the primary energy-balancing mecha-nism of the building, the architectural filters. There-fore, machines should be as efficient as possible in us-ing fuel or electricity to condition the space. The way in

which conditioning is delivered should be comfortable,without drafts or uncontrolled cooling or overheating.Most importantly, the aesthetic impact of the machinesshould be consistent with the architectural intention,both within the space and on the building envelope.

Does the building need to be sealed to be energyefficient?Many mechanical engineers prefer sealed buildingsbecause they are easier to control, to balance and to

deliver the controlled range of temperature and humid-ity. However if exterior conditions are comfortable andnatural ventilation can be used, it will be more energy

efficient to open the building during those times andto turn off the mechanical system. This building is thenconsidered a mixed-mode building. As codes adjust topressure from architects and owners, naturally-ventilat-

ed and mixed-mode buildings are gradually becomingthe norm.

Is thermal comfort different in a sealed buildingas opposed to a mixed mode building?The prevailing comfort standards used by mechanicalengineers (ISO 7730 and ASHRAE 55) define a range oftemperatures and humidity levels at which most people

say they are comfortable. The standards assume staticindoor conditions that are common to mechanicallyconditioned buildings, regular business clothes andbehavior. Research has shown that people describe


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tools and software


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Model being tested in a boundary-layer wind tunnel. Image courtesy of P.W.Hildebrand.

Iterative testing of facade design for cross ventilation. Image courtesy of P.W.Hildebrand.

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How to measure air speed in a building?Air speed is measured with an anemometer and the units are metersper second or kilometers per hour. Wind vane type meters have low-er sensitivity than do hot wire type meters. To get an accurate readingplace the device perpendicular to the flow of air. Most air sources arevariable, particularly at lower velocities, so take multiple readings overa period of several seconds until you find a concensus air speed.

See Day 2 for other thermal comfort measurements: thermometer,

hygrometer, radiant thermometer, IR camera. See Day 2 for climateand site analysis, energy modeling, and comfort modeling.

How to predict air movement?Wind tunnels are laboratory scale facilities that generate a known airstream for use with physical models. While many wind tunnels are

used to study the aerodynamics of aircraft, cars and space vehicles,the flow patterns of wind and air around and within buildings requirea boundary layer wind tunnel to simulate the turbulence of the earths

surface. Wind tunnels can generate data for the velocity, direction of

flow and pressure variations in and around buildings. They also enablevisualization of the flow patterns but cannot easily model thermallydriven air movement such as stack ventilation.

Computational fluid dynamics (CFD) uses algorithms and calculationsto simulate situations that involve fluid flows, including the flow ofair. CFD analysis is increasingly used to study complex air flows andthermally driven air movement in and through building components

(such as double skin facades) and urban spaces between and aroundbuildings. While CFD offers some advantages compared to wind tun-nel testing and simplified rules of thumb, there remain many problemswith the ability of the computer power to handle the complex condi-tions of architecture. CFD validation still requires wind-tunnel data andthis is likely to be the case for the foreseeable future.



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CFD analysis of wind pressures on a bus and ferry terminal.

Ventilation requires nearly 75% less air volume to be delivered than thermal conditioning.

When occupants control their environments they have a greater range of tolerance for temperature and humid-ity variation.

Air speed thresholds for conditioned and naturally-ventilated buildings:0.20 mps barely noticeable1.00 mps upper limit for air-conditioned space, good for natural ventilation in hot/dry climates2.00 mps natural ventilation in hot/humid climates

4.60 mps gentle breeze outdoors

Air movement against the skin, even when its warm air, canhave a cooling effect of 2-4C.

Ventilation inlets should be oriented perpendicular to prevail-ing winds.

The more the architecture and the envelope create comfort-able conditions for the occupants, the less mechanical equip-ment is needed. This results in a lower first cost for the machinesand the energy to operate the building is reduced, resulting in asmaller carbon footprint.

Websites

National Institute of Building Sciences (www.wbdg.org/resources/naturalventilation.php)University of Hong Kong, Faculty of Architecture (www.arch.hku.hk/teaching/lectures/airvent/sect03.htm)NIST Natural Ventilation Resources (fire.nist.gov/bfrlpubs/bfrlall/key/key3263.html)

BooksArchitectural Aerodynamics by R.M. Aynsley, W. Melbourn, and B.J. Vickery. London: Applied Science Publish-ers,1977Natural Ventilation in Buildings: A Design Handbookby Francis Allard and Mat Santamouris, (Best (Buildings, Energyand Solar Technology))

Moving Air for Comfortby Ed Arens et al. Original Citation: ASHRAE Journal, May 51 (25), 8 18, 2009 1. Can bedownloaded: escholarship.org/uc/item/6d94f90bHigh-Performance Buildingby Vidar Lerum. Hoboken, N.J. : John Wiley & Sons, 2008


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equation for cross ventilation cooling

qV = 1.2 V dT

= 1.2 (1000 Cv A v) (Tin - Tout)

qV = energy lossV = flow rate (L/s) = 1000 Cv A vCv = wind direction relative to bldg * 0.50 0.60 (perpendicular); 0.25 0.35 (diagnol)A = smaller of inlet or outlet area (m2) * must account for window operationv = velocity of air (m/s)dT = (Tin Tout)* outside temp must be less than inside

equation for stack ventilation cooling

qV = 1.2 V dT

= 1.2 (0.65 A (9.81 h (Tin - Tout) / Tin)) Tin - Tout

qV = energy lossV = flow rate (L/s) = K A (g h (Tin Tout) / Tin)K = discharge coefficient = 0.65A = smallest area of inlet, throat, outlet (m2)g = gravitational constant = 9.81 m/s2h = height from inlet to outlet (m)Tin = interior temperature (K)Tout = outside temperature (K)dT = Tin Tout (K) * outside temp must be less than inside

Cooling capacity of stack ventilation dependent on stack area, floor areabeing cooled, and height of stack. Adapted from Kwok 2007, 147.

Cooling capacity of cross ventilation dependent on inlet area, floor areabeing cooled, and wind velocity. Adapted from Kwok 2007, 147.


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day four: energy


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Adapted from Brown 2001, 224.


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english-japanese dictionary


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Aerodynamic(s)

Aerogel

Air Conditioner

Air distribution

Air duct / /

Air handling unit Air motion

Air supply

Air temperature

Anemometer

Artifi cial lighting

Candela

Central Heating

Chilled water

Clerestory

Climatic chart

Climatic region

Comfort zone

Condensation

Conditioned air

Conduction

Convection

Cross ventilation

Daylight Daylight factor

Dehumidifi cation

Dew point temperature

Double glazing

Dry bulb temperature

Duct

Emissivity

Energy Energy conservation

Exhaust air (gas)

Existing conditionsanalysis

Fan /

Field measuring

Floor heating Foot candle

Geothermal energy

Glare

Heat capacity

Heat exchange

Heat gain

Heating / heater

Heat pump /

Heat transfer

Hot air system

Humid air

Humidity

Illuminance

Illuminance distribution


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Insulation

Laminated glass

Latent heat (storage) () ()

Lighting

Luminance

Luminance meter

Luminance ratio

Lux Mean radiant tem-perature

Mechanical ventilation

Mixed mode

Natural ventilation

Negative pressure

Outdoor air Passive solar

Photometer

Photovoltaic cell (PV) /

Prevailing wind direc-tion

Psychrometric chart

R-value R Radiant energy

Radiant heat

Relative humidity

Return air

Saturated moist air

Schematic diagram

Sensible heat

Simulation

Sky brightness (or skyluminance)

Solar altitude

Solar azimuth

Solar radiation

Specifi c heat

Sun path diagram

Temperature

Thermal capacity

Thermometer

True north

True solar time

U value U Unit air conditioner

()

Unit heater

()

Vapor barrier

Ventilation

Watt

Wet-bulb temperature

Wind tunnel / channel

Wind direction

Window

Wind pressure

Wind speed / velocity

works cited


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Brown, G.Z. and Mark DeKay, Sun, Wind & Light, 2nd Ed. New York: John Wiley & Sons, 2001.

Kwok, Alison and Walter T. Grondzik, The Green Studio Handbook. New York: Architectural Press, 2007.

Lechner, Norbert. Heating, Cooling, Lighting, 3rd Ed. New York: John Wiley & Sons, 2009.

Moe, Kiel. Thermally Active Surfaces in Architecture. New York: Princeton Architectural Press, 2010.

Moore, Fuller. Concepts and Practice of Architectural Daylighting. New York: Van Nostrand Reinhold Company,

1985.

Olgyay, Victor. Design with Climate. Princeton, NJ: Princeton University Press, 1963.

Robbins, Claude. Daylighting Design & Analysis. Van Nostrand Reinhold Company, 1986.

Schittich, Christian, Solar Architecture. Boston: Birkhauser, 2003.

Stein, Benjamin, John Reynolds, Walter Grondzik and Alison Kwok, Mechanical and Electrical Equipment for Build-

ings, 10th ed. New York: John Wiley & Sons, 2006.

architecture energy 2011

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