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Environmental Systems > Terms 01 > Flashcards

Terms 01 Flashcards

1
Q

EUI

A

Energy use intensity.

kBTU/sqft/yr - the amount of energy used in the building, per sqft or sqm of floor area.

Common metric for determining site energy use.

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2
Q

Site Energy

A

MMBTU - total amount of energy used at the building’s site

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3
Q

Source Energy

A

MMBTU - total amount of energy that goes into producing the energy on site, but at the originating power plant.

The diff between source energy and site energy is losses in transmission and efficiency.

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4
Q

BTU

A

British Thermal Unit, energy measurement

The amount of work needed to raise the temperature of one pound of water by one degree Farenheight

1 BTU = 0.00029 KWh = 1055.06 Joules

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5
Q

kW

A

Kilowatt, energy measurement

1000 Watts

1 Watt = 1 Joule (measure of work) per second

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6
Q

HVAC

A

Heating, ventilation, and air conditioning. Mechanical systems

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7
Q

HDD

Heating Degree Day

A

degrees (avg) per day of heating needed to reach thermal comfort mean temperature.

Often summed across multiple days to achieve seasonal or annual measure.

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8
Q

CDD

Cooling Degree Day

A

degrees (avg) per day of cooling needed to reach thermal comfort mean temperature.

Often summed across multiple days to achieve seasonal or annual measure.

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9
Q

Heating Dominated / Cooling Dominated

A

the dominant need for comfort remediation

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10
Q

Sensible Heat

A

Heat change (transfer of energy) that impacts the direct feeling of temperature.

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11
Q

Latent Heat

A

Heat change (transfer of energy) within a phase change (sold - liquid - gas) and that does not impact a change in the direct feeling of temperature.

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12
Q

Dry Bulb Temperature

A

(deg F / deg C) Amount of heat in the air, w/o consideration of humidity.

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13
Q

Wet Bulb Temperature

A

(Deg F / deg C) Amount of heat on a moist thermometer.

takes wind and evaporative cooling into account for a “feel” of temperature.

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14
Q

Dew Point

A

(deg F / deg C) Temperature at which condensation forms.

Air has reached 100% relative humidity, or the point of saturation.

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15
Q

Absolute Humidity

A

(lb or g water per lb or g dry air) Actual amount of moisture in the air.

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16
Q

Relative Humidity

A

(%) Amount of moisture that the air can hold (inversely related to temperature - warmer air can hold more moisture)

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17
Q

Direct normal Illuminance / radiation

A

light (lumens) / radiation (watts) hitting perpendicular to a surface, coming from a 5.7 degree cone of view centered on the sun.

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18
Q

Diffuse Radiation

A

Radiation coming from all directions other that the view cone of direct normal.

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19
Q

Global Horizontal Illuminance / Radiation

A

Light / Radiation hitting a flat ground plane, from all directions (direct and diffuse). Often used as a measure of diffuse light / radiation.

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20
Q

Clothing Level

A

(Clo, similar to R) Insulation value of clothing or a clothing assembly

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21
Q

Activitiy Level

A

(Met, metabolic rate) Heat output of a person, based on physical exertion levels.

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22
Q

PMV

A

Predicted Mean Vote.

Numberic scale (-3 … 0 … 3). Analytic and Survey metric of Too Cold to Neutral to Too Hot human comfort.

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23
Q

PPD

A

Percent People Dissatisfied

Statistical measure of human satisfaction with an environment.

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24
Q

ASHRAE Standard 90.1

A

Baseline energy cod of minimum standards of energy performance related to the construction of buildings,

their thermal and comfort performance, and human health

90.1 is baseline code adopted by many states and some countries, and incorporated into their unique energy and buillding codes

American Society for Heating, Refrigeration, and Air Conditioning Engineers

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25
Q

ASHRAE Standard 55

A

Standards definig human comfort and thermal environments.

Used as extension and subset of Standard 90.1

Standard 55 generally does not define code but rather conditions and criteria to target in design.

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26
Q

Natural Capital

A

Lovins, Lovins, Hawken

1) Dramatically increase productivity of natural resources
2) Shift to biologically inspire production models
3) Move to a solutions-based business model
4) Reinvest in natural capital

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27
Q

Insolation

A

(BTU/sq ft, W/sq m) The amount of solar radiation hitting a given surface

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28
Q

Altitude

A

(deg) The vertical angle from the horizon up into the sky of an object, in this case the sun.

0 degrees = horizon
90 degrees = straight up in sky, perpendicular to earth’s surface

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29
Q

Azimuth

A

(deg) The horizontal angle of rotation along the earth’s surface of an object

Usually measured from North (0 degrees) clockwise to 90 (East), 180 (South), 270 (West), 360 (North). Some conventions measure instead from South as 0 degrees.

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30
Q

Bearing

A

(deg + Direction) The horizontal angle of rotation along the earth’s surface of an object , usually measured from North (0 degrees) and going in either direction (E or W) by an angle or rotation. Thus 90 degrees E is = 90

thus 90 degrees E = degrees Azimuth
90 degrees W = 270 Azimuth

again some conventions measure 0 as south

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31
Q

Latitude

A

(deg) The angle measured N or S around the earth from the equator (0) to either the N or S poles.

Charlottesville is at 38.0293 N

NYC is at 40.7128 N

Note that the degrees latitude also marks the altitude of the sun at noon on the euqinoxes for a given location

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32
Q

Longitude

A

(deg) the angle mueasured around the earth’s rotation, starting from the Prime Merideian (0) which passes through Greenwich, England (southeast London) and proceeding to the east.

Western locations have a negative latitude.

Note that latitude has no direct consequential relationship to solar geometry, as the earth rotates equally along all longitudes.

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33
Q

Angle of Incidence

A

(deg) The angle of incoming relationship of a ray to any given surface, measured against the normal direction (perpendicular, 90 degrees) to that surface.

The smaller the angle of incidence (approaching 0 degrees diff from the normal), the more direct the ray is to that surface.

The greater the angle of incidence (approaching 90 degrees difference from the normal), the more askew the ray is to that surface.

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34
Q

Lambert’s Cosine Law

A

states that the intensity of radiant or luminous energy received by a surface is directly proportional to the cosine of the angle of incidence.

Therefore, the received energy will be greatest when the angle of incidence is 0, or pointing directly at the surface (since the cos(0) = 1), and the received energy will decrease as the angle of incidence increases (as the angle becomes more askew), since the co(90)=0

35
Q

PV - Photovoltaics

A

A technology, and its products also commonly called a solar array, that converts incident light energy into electricity.

36
Q

Passive Solar

A

using physical / architectural conditions (windows, orientation, materials, thermal mass) to heat a building or space using the sun, and reduce the need for mechanical or electrical heating energy.

37
Q

Active Solar

A

using technical equipment add-ons to convert sunlight into electricity (PV)

38
Q

Solar Envelope

A

The volume and faces / edges of that volume where-in a building can be placed so as to not impede or shadow adjacent buildings or locations form the sun.

The solar envelope is determined directly from the altitude and azimuth angles of the sun from a given site, in combination with the adjacent region not to be shaded, and the number of acceptable hours o shade allowed or sun required.

39
Q

Solar Zoning

A

Municipal Zoning laws that specify solar envelope constraints on new or renovated buildings, for the purposes of meeting passive solar, day-lighting, or active solar outcomes.

40
Q

Right to Light

A

a form of easement in English law that gives a long-standing owner of a building with windows a right to maintain the level of illumination

based on Ancient Lights law, and in modern law, the Prescription act 1832

41
Q

Lumen

A

SI unit of light measurement

more specifically luminous flux

The amount of light emitted per second in a solid angle of one steradian from a uniform source of one candela.

1 lm = 1 cd x sr

42
Q

Candela

A

SI unit of luminous intensity.

The amount of luminous intensity emit by a single common wax candle.

43
Q

Watt

A

unit of power measurement.

1 Joule (measure of work) per second.

Does NOT measure light

44
Q

Solid Angle

A

a volumetric three-dimensional angle within a portion of a sphere.

(a regular angle is planar)

A full sphere has 4pi steradians (square radians)

45
Q

Lux

A

lumen per square meter.

a measure of illuminance.

46
Q

Footcandle

A

lumen per square foot

a measure of illuminance

47
Q

Illiminance

A

(lux/footcandles) the amount of light hitting a surface. (alt. incident upon or incoming to.)

Required lighting levels depends on activity.

Office typ: 28fc / 300lux
School typ: 37fc / 400 lux

See the IES Footcandles Recommendations for details.

48
Q

Luminance

A

(lux/footcandles) the amount of light leaving a surface, usually from reflection off of the surface.

49
Q

Reflectance

A

(decimal percentage) The ratio of light reflected off of a given surface (luminance) compared to what came into it (illuminance).

Usually based on that surface’s material properties, including color.

White surfaces have high reflectance. Dark surfaces have a low reflectance.

Reflectance = luminance / illuminance

50
Q

Color Temperature

A

(K) the temperature of a black-body radiator that emits light comparable to the color of a certain light source.

Color temp is practically used to measure the character sharpness of light..

Cooler lights (blue/white are over 5000 K while warmer lights (yellow-white / red) are 2700-3000K

51
Q

Inverse-Square Law

A

the law that states that the intensity of energy (radiation, illuminance, etc) from a source falls-off (reduces) according to the square of the dist from the source

Thus a surface twice the dist from a source will receive 1/4 of the light or radiation as compared to the original, and a surface 3 times the distance will receive 1/9.

52
Q

Luminaire

A

a light fixture. Any a complete lighting unit consisting of a lamp or lamps together with the parts designed to distribute the light, to position and protect the lamps, and to connect the lamps to the power supply

–from IES Lighting Handbook and 2014 National Electric Code

53
Q

Photometric / Candela Distribution

A

A set of data

including 2 and 3 dim distribution intensity graphs, that describe the shape and throw of light from a luminaire

54
Q

IES File

A

(.ies file format) a standard data file format to describe the photo-metrics and candela distribution of a given luminaire.

Lighting and luminaire manufacturers publish .ies files for their products for use by architects and lighting designers.

55
Q

Incandescent Light Bulb

A

a light bulb (lamp) using an electric resistance filament that glows with visible light (incandescence) when heated by flowing electric current.

Very inefficient (produces more heat than light).

Invented (refined) by Thomas Edison and others

A typ 60 watt incandescent bulb produces approximately 800 lumens.

A typ 100 Watt incandescent bulb produces approximately 1600 lumens.

56
Q

Compact Flourescent Light Bulb (CFL)

A

a light bulb (lamp) using excited electrons and mercury atoms to radiate ultraviolet light, which converts to visible light when it hits the bulb’s fluorescent coating.

A typ 13 Watt CFL produces the same 800 lumens as a 60 Watt incandescent.

57
Q

LED Light Bulb (Light Emitting Diode)

A

a light bulb (lamp) using LED electroluminescence technology of many smaller LED units collected together to produce and direct light equivalent to other traditional lamps form factors and intensities.

LEDs are quickly replacing other lamp technologies in residential and commercial settings.

A typ 9 Watt LED bulb produces the same 800 lumens as a 60 Watt incandescent.

58
Q

The Sun

A

ASTM (2014) solar illumination constant = 133.1 kilolux (IES 2010)

100 kilolux (100,000 lux) received on the earth’s surface, form an unobscured sun

The earth sees ~1/175,000 steradian. The sun emits 2.2 billion times the radiation that we see.

59
Q

Right to Light

A

An Ancient British law protecting a property owner’s access to light and solar radiation through windows on their building once it is established, and preventing an adjacent property owner from constructing any obstruction or shadow of that light.

60
Q

VLT Visible Light Transmittance

A

The factor (range 0-1) of available light (lumens) that is transmitted through glass.

Contributes to day lighting.

61
Q

SHGC

Solar Heat Gain Coefficient

A

The factor (range 0-1) of available solar radiation (Watts) that is transmit through glass.

Contributes to heating/cooling.

Helps heating and hurts cooling

62
Q

Daylight Factor

A

(%) The ability of a space to bring in daylight from the outside.

Specifically, the ratio of indoor illumination at a given point to outdoor illumination at the same height.

Calculated using a uniform cloudy sky, with no direct sunlight. The factor is not climate-based or location dependent.

63
Q

sDA

Spatial Daylight Autonomy

A

(%) To what degree can a space use natural day lighting instead of artificial to meet illuminance needs of a space.

TYP use: sDA 300/50 = percent of floor receiving at least 300 lux during at least 50% of occupied hours.

This metric is climate-based (based on TMY weather data) and location dependent.

64
Q

ASE

Annual Sunlight Exposure

A

(hours) Exposure to direct sunlight at a given point in the building. (used in Sefairaa to help determine over-lit vs under-lit conditions)

TYP use: ASE 1000/250 = percent of floor receiving at least 1000 lux for at least 250 occupied hours.Too much direct illumination = problems with glare.

65
Q

cDA

Continuous Daylight Autonomy

A

(%) Very simimlar to sDA, except that sDA only gives credit to a location if the illuminance is greater than 300 lux or other illuminance levels specified. This would not give any credit for 299 lux. cDA on the other hand gives partial credit (scaled) to daylight illuminance below the threshold value, and is often considered more effective of a metric, even though LEED does not use it.

The theory is that lesser values still contribute to the daylight autonomy of the space, even if not meeting the singular numeric threshold.

66
Q

UDI

Useful Daylight Illuminance

A

(lux / footcandles) Specifies three specific buckets of illuminance values:

too low: (0-100 lux)
useful: (100-2000 lux)
too much: (>2000 lux))

to judge the daylight spread and quality of a space. This is similar to combining sDA and ASE illuminance ranges into a single view, except that UDI does not include an occupancy hours metric, only illumination ranges.

67
Q

Glare

A

Too great of a difference in lighting levels between two surfaces with a person’s visual field. This makes your eyes hurt for trying to constantly adjust between them.

68
Q

Daylight REsponse

A

mechanism to respond to and control the amount of light in a space (both daylight and artificial), through things like operable shading, blinds, occupancy sensors, daylight switches, etc.

69
Q

SAD Syndrome

A

Seasonal Effective Disorder..

A medical / psychological condition in which persons not receiving enough natural daylight or who receive it under erratic patterns experience changes in their natural circadian rhythms and exhibit depression-like symptoms.

70
Q

HEAT FLUX (thermal flux) (q)

A

The transfer of heat through a material or assembly of materials. Specifically, the flow of energy per unit area per unit of time.

71
Q

Emissivity

A

(ratio 0-1) m material surface’s ability to give off heat as radiation. Typ value 0.85-0.9 Specifically, the ration of energy radiated from a surface compared to that radiated from a blackbody at the same temperature and wave length under the same viewing conditions.

72
Q

Conduction

A

The transfer / transmission of energy (heat, or other type) through a material.

Total energy will either reflect back, absorb into, or transmit (conduct) through.

73
Q

Conductivity (k)

A

(k) (W/mK, BTU/hr ft F) a material’s ability to conduct heat. (through the linear thickness)

74
Q

Conductance (U)

A

(W/mK, BTU hr ft F) an object’s (wall, roof, etc.) ability to conduct heat. (across a surface area of the object)

75
Q

U-Value / U-factor

A

(W/mK, BTU/hr ft F) the unit of conductance. (0.77 BTU/hr ft F is typical 4” thick fiberglass batt insulation.

76
Q

Resistance (R)

A

(m2k/W, hrft2°F/BTU) Ability of an object (wall, roof, etc.) to •not• conduct heat

77
Q

R-Value

A

Thermal resistance of wall assembly.

Inverse of U-value (1/U).
R-13 is typical 4” thick fiberglass batt insulation

78
Q

Denisty

A

(kg/m3, lb/ft3) The amount of material (mass) in a given volume (space).

79
Q

Specific Heat

A

(cal/g°C, J/kg°K, BTU/lb°F) – The thermal capacity of a material.
The number of calories (or BTU) required to raise the temperature of 1 gram (or pound)
of a substance 1°C (or 1° F).

80
Q

Thermal Mass

A

(Cth) – (J/°C, J/°K, BTU/°F) The ability of a body to store thermal energy.

In buildings, this provides inertia against temperature fluctuations as well as the capability for retention and re-radiation of heat (and conversely cool).

81
Q

SHGC,

Solar Heat Gain Coefficient

A

(decimal / percentage 0-1)

The percentage of incident solar radiation (heat) that is transmitted through glass.

82
Q

VLT

Visible Light Transmittance

A

decimal / percentage 0-1)

The percentage of incident light (lumens) that is transmitted through glass.

83
Q

Low-E (Windows)

A

A coating or film that reduces emissivity, or the ability to radiate heat.
Low-E coatings are a typical component of higher-performance windows.

Environmental Systems (1 decks)

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