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Flashcards in Building Services Engineering Deck (117)
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1
Q

Indoor Comfort Dependencies

A

Thermal - Thermal Environment
Acoustic - Sound Level
Visual - Luminance / glare / daylight
Indoor Air Quality - Indoor Pollution / Air Quality

2
Q

Thermal Comfort Definition

A

That condition of mind which expresses satisfaction with the Thermal Environment

3
Q

Issues caused by over/underheating

A
37 Overheating 34 Undercooling
Heat stroke
Heat Exhaustion
Frostbite
Hypothermia
4
Q

Fangers 7 Point Thermal Scale

A
3 - Hot
2 - Warm
1 - Slightly Warm
0 - Neutral
-1 - Slightly Cold
-2 - Cool
-3 - Cold
5
Q

Fangers Considerations

A

Environmental - Air temp, Mean radiant temp, Air velocity, Relative humidity
Personal - Metabolic rate, Clothing insulation

6
Q

Mean Radiant Temperature

A

Average effect of temp from surrounding surfaces

7
Q

Operative Temperature

A

Meausred by combining air temperature, mean radiant temperature and air speed

8
Q

Three modes of Adaption

A

Behavioural Adjustment Adaption - Adaptive actions when uncomfortable
Physiological adaption - Heritage / acclimatising
Psychological adaption - alter perception expectation

9
Q

Adaptive Thermal Comfort Model

A

Linking people comfort temperature indoors with temperature outdoors in naturally ventilated buildings

10
Q

Radiant Asymmetry

A

Ration heat gain/loss from different sides of the body

11
Q

Solid / Liquid / Gaseous Pollution

A

Solid - Dusts / fumes / smokes
Liquid - Mists / fogs / smokes by tars in cigarette smoke
Gaseous - SO2 / CO

12
Q

Indoor Pollutant Sources

A

Paints / Adhesives / Smoking / Moulds

Co2 respiration / skin particles / Odours

13
Q

Filters

A

Efficiency 20-90%
Type depend on application
Check / clean / replace periodically

14
Q

Illuminance

A

Total luminous flux incident on a surface per unit area (Lux)
Measure for brightness

15
Q

Daylight

A

Combination of all direct and indirect sunlight during the daytime

16
Q

Sick Building Syndrome

A

A range of symptoms attributed to spending time in a certain building

17
Q

SDS Factors

A

Poor maintenance / management
Lack of control over environment
Poor design
Poor indoor air quality

18
Q

Types of Ventilation

A

Natural - Least improving Comfort Ventilation
Mechanical Ventilation
Comfort Cooling
Air Conditioning
Close Control Air Conditioning - Most cost

19
Q

Wind Driven

A

Wind entering through windows on all floors

20
Q

Buoyancy / Stack Driven

A

Enters and heat gains from the inside makes it rise through the building
Low pressure sucks in air

21
Q

Scoop Ventilation

A

Using the direction of the wind to channel through stack to other parts

22
Q

Ducted Ventilation

A

Wind directed by ducts to other parts of the building rising / falling

23
Q

Disadvantages of Natural Ventilation

A
Air Pollution
Noise
Overheating
Poor Security
Lack of control
24
Q

Advantages of Ventilation

A

Cheap, Simple and Renewable
No / Little maintenance
Occupant controlled

25
Q

Occupant Behaviour Definition

A

If a change occurs such as to produce discomfort, people react in ways that tend to restore their comfort

26
Q

Adaptive Behaviour Examples

A

Fans
Shading devices
Clothing
Activity levels

27
Q

Retrofit Measures

A

Improve air tightness
Upgrade external wall insulation
Upgrade roof insulation
Increasing window layers

28
Q

Heat Losses / Gain

A

Ventilation
Infiltration
Conduction through building fabric

Solar / People / Equipment / 3 abve

29
Q

What makes up a conventional heating system

A
Fuel
Heat Source
Heat transfer medium water/air etc + pipework
Power
Heat Emitters
Control devices
30
Q

Pump in Series vs Parallel

A

Series - Same flow rate

Parallel - Same pressure

31
Q

Expansion tank configuration

A

Open Tank - Open to atmosphere
Closed Tank - Captured air
Diaphragm Tank - Membrane inserted between air / water

32
Q

Single Pipe System

Two / Dual Pipe

A

One pipe to everything

Hot Feed + Cold Return

33
Q

Heat Emitters

A
Radiators 
Convectors
Underfloor Heating
Radiant Heating
Air Handling Units
34
Q

Radiator Pro’s / Con’s

A

Temp Control / low maintenance

Slow thermal response / Impact floor layout

35
Q

Natural Convector

A

Room air pulled in
Finned heating tube
Warm air out

36
Q

Air Handling Unit

A
Air
Noise attenuator 
Frost coil
Filters
Cooling coil
Re-heat coil
Fan
Humidifier
Noise attenuator 
Duct
37
Q

Fan Coil Unit

A
Air
Filter
Cooling Coil
Heating Coil
Fan
Conditioned air
38
Q

Metals with low resistance

A
Copper
Aluminium
Platinum 
Gold
Silver
39
Q

Electric Current Effects

A

Heating - Heat
Magnetic - Magnetic field
Chemical - Electrolysis

40
Q

Ohm’s Law

A

V=IR
Volts
Amps
Ohm’s

41
Q

Energy Equations

A

Energy = Power x Time

42
Q

Inductance vs Capacitance

A

Inductance - induction of voltages in conductors self induced by the magnetic fields of currents
Capacitance - Electrostatic storage of charge induced by voltages between conductors

43
Q

Inductance Examples

A

Motors
Heating Coils
Lighting chokes

44
Q

CHP

A

Combined Heat and Power

Heat engine to generate electricity and useful heat

45
Q

Transformer Equation

A

Vprimary / Vsecondary

Isecondary / Iprimary
Used to change voltage and current

46
Q

Medium Voltage Switchgear

A

Switch / protect cables against faults
MV distribution network or intake
Air / vacuum circuit breakers

47
Q

Low Voltage Switchgear

A

Large intake can be split to serve smaller loads
Protective devices to protect cables and equipment
Moulded case circuit breakers

48
Q

Busbars

A

High Power Loads

Use less space than multiple power cables

49
Q

Distribution Boards

A

Receive feed from main switchboard

Feed out to smaller local circuits such as lighting and small power

50
Q

Water Treatment Process

A

Coagulants added, Heavy particles stick
Heavy particles drop, removed, fertiliser
Filtered through fine materials
Disinfectants added
pH maintained by adding Alkaline substances

51
Q

Alternative Supplies of Water

A

Wells / boreholes
Springs / streams
Reclaimed water (rainwater)
Bottled water

52
Q

Grey Water

A

Relatively clean water from baths, sinks and washing machines etc
Toilet / Garden Use / Cleaning

53
Q

Incoming water supply

A

Incoming water supply from utility mains
Isolation value
Water meter

54
Q

Water Heater Types

A

Direct Gas fired Water Heater
Electric Water Heater
Solar Water Heating

55
Q

Mechanical Ventilation Definition

A

Movement of air through a building using fan power, filtration and heating of the air

56
Q

Why Ventilate

A

Provide fresh air ventilation
Fume control
Cool the building

57
Q

Effective Ventilation

A
Provide Oxygen
Reduce Co2 build up
Control body odour
Minimise effect of some smoking
Minimise effect of heavy smoking
58
Q

Domestic Ventilation System

A
Internal Grille
Fan Module
Fan Spacer
Sealing Plate
External Grille
59
Q

3 Types of Mechanical Ventilation

A

Filtration Only
Filtration + Heating
Filtration + Heating + Cooling

60
Q

Duct Sizing

A

Static Regain
Equal Pressure Drop
Velocity Method

61
Q

Static Regain

A

Long lengths of high velocity

Duct gets bigger to maintain velocity after branches to increase static pressure

62
Q

Equal Pressure Drop

A

Duct size reduces through system

63
Q

3 Fan Types

A

Backward Curved Fan - Lower Volume Higher Pressure (high efficiency)
Forward Curved Fan - High volume system (low noise lower efficiency)
Axial Fan - High Volume Low Pressure system (Higher noise)

64
Q

Duct Work Shape

A

Circular - Most efficient / cheap
Rectangular - Greatest flexibility in aspect ratio
Flat Oval - Most expensive

65
Q

Duct Materials

A
Hot Dip Galvanised Steel 
Plastic
Stainless Steel
Aluminium 
Pre-Costed Steel
66
Q

Thermal Comfort Factors

A
Temperature
Humidity
Air Velocity
Clothing
Direct radiation
67
Q

Air Conditioning Components

A

Filters
Heating Coil
Cooling Coil
Humidifier / De-humidifier

68
Q

Psychometric Chart

A

Psychrometric processes of air

dry bulb temp / wet bulb temp / humidifier / enthalpy / air density

69
Q

Displacement Flow

A

Piston Flow - Air moved slowly, prevents pollutants being mixed
Displacement Ventilation - Air introduced low level, convection currents to high, extract high

70
Q

Mixed Flow

A

Mixes pollutants with room air
Suitable with mobile pollution source
Uniform temp distribution

71
Q

Diffuser Terminology

A

Throw - Distance to which jet has slowed to terminal velocity
Buoyancy Effect - Jet drop / rise
Surface Effects - Air discharged clings to ceiling Coanda Effect

72
Q

Building Fabric Serves to…

A
Protect building from weather
Provide Privacy
Provide Security 
Regulate indoor environment
Transmission of Noise
73
Q

Window Properties

A

Reflectance - Ratio of luminous flux reflected to flux incident
Transmittance - Ratio of luminous flux transmitted to flux incident
Absorbstance - Ratio of luminous flux absorbed to flux incident

74
Q

Thermal Mass

A

High Heat capacity

High Density

75
Q

Double Skin Facade

A

Warm - Warm air rises and draws cooler from bottom

Winter - Draws in cold air and heats it

76
Q

Double Skin Facade Adv/Dis

A

Acoustic Insulation / Thermal insulation / Reduce wind effect
Reduces space / Weight increase / Cost

77
Q

Low-E (emissivity) Windows

A

Minimise the amount of UV and IR that can pass without compromising the visibility

78
Q

Switchgear

A

Combination of disconnect switches, fuses and circuit breakers to protect and isolate electrical equipment

79
Q

RMU

A

Cheaper than panel boards
Outdoor use
Bottom entry

80
Q

LV / MV Switchrooms

A

Easy maintenance
Ventilation to dissipate heat
Allow space for extension

81
Q

Building Service Principle

A

Decrease energy demand
Maintain a constant load
Improve efficiency of energy required

82
Q

Ways of Affecting Form

A

Physical - Space planning / concealing services
Visual - Exposing services
Performance - env perf / reduce need for systems / equip

83
Q

Physical space for services

A

Space for equipment plant room and risers
Vertical distribution
Horizontal distribution
Air plant on roof energy plant basement

84
Q

Space for Equipment

A

All air system 3-5%
Eletrical, boilers, chillers, water 1-2% floor area
Total area 5-11%

85
Q

Orientation and Massing

A

Position building to capture sun for heating

Reduce east and west exposure because of low sun angles

86
Q

External Shading

A

Protect solar gain
Reduce glare
Reduces radiant temperature of glass
Controlled to allow daylight

87
Q

Refrigerant

A

Phase change from gas to liquid to gas

88
Q

Refrigeration Cycle Components

A

Compressor - Compresses refrigerant incr temp / pressure
Condensor - Release heat to ambient environment
Expansion Valve - Expand refrigerant to decrease pressure and temperature
Evaporator - Absorb heat from the indoor environment

89
Q

Factors considered for refrigerant

A

Low specific volume
High latent heat
High thermal conductivity
Low viscosity

90
Q

4 Refrigerant Groups

A

Inorganic
Organic
Zeotropes
Azeotropes

91
Q

Environmental factors affecting building shape

A
Sun
External temperature range
Wind 
Rain
Noise
92
Q

System Approaches Priority Rank

A

Natural Ventilation
Mechanical Ventilation
Mechanical Cooling or Air Conditioning

93
Q

Mechanical Ventilation Pros / Cons

A

Easily controlled
Greater flexibility in floor plan design
Energy Required / service costs

94
Q

Mechanical Cooling Pros / Cons

A

Flexibility in building layout
Can offset heat gains from equipment / people etc
Control over internal environment Temp/Humidity/Air flow/Noise
Energy / service costs

95
Q

Effect on building Form
Energy Use
Effect on floor Plan

A

Natural / Mechanical / Mech Cooling
Sig / Less Sig / Least Sig
Low / Medium / High
High / Minimum / Minimum

96
Q

FCU’s

A

Fan Coil Unit
Air cooled in the space by fan coil in ceiling
Air recirculated and mixed

97
Q

Define Voltage

A

Voltage is a measure of a systems ability to do work moving charge (-ve electrons) around an electrical circuit. (A house has 230V in outlets).

98
Q

Resistance Depends Upon

A

The material type
Cross-sectional area
Length
Temperature

99
Q

Most effective way of converting thermal energy into heat Electricity

A

Turbine Driven Alternator that turns coils producing alternating current. Direct current are batteries created through a chemical reaction

100
Q

Drax Power Station

A

Generators fitted with FGD (Flue Gas Desulphurisation)
Removes 90% of the sulphur dioxide from emissions
Direct injection allow biomass injected directly into boiler.

101
Q

IEE Wiring Regulations (BS7671)

A

Tells you how to size cables
Current carrying capacity
Fault conditions
Voltage drops

102
Q

Transformers

A

Used to charge voltage and therefore current

Transmit at high voltage to avoid heat loss

103
Q

Air Conditioner How it works

A

Liquid is sent through coils and evaporates
This makes the coils very cold
Air is passed over these coils to cool your house
Gas goes through a compressor to a turn back to liquid

104
Q

Why use ductwork

A

Delivery to and from spaces
Required air volume known
Central plant to rooms
Reduces leakage and space requirement

105
Q

Factors influencing duct design

A

Duct Size

Effect of velocity

106
Q

Setting Duct Size

A

Small is cheaper
Friction in duct work increases power
Power = Pressure x Flow Rate

107
Q

Duct Extractions

A

Kitchen / Dust / Chemical

108
Q

Static Regain Adv/Dis

A

A size for all ductwork
Self balancing system
Energy Efficient
Not applicable to extract systems

109
Q

EPD Adv/Dis

A

Quick and easy
Gives reductions at branches
Commercial building with complex routes
Use more energy than static regain

110
Q

Velocity Adv/Dis

A

Avoids noise issue
Simple Sizing approach
Widely used

111
Q

MRT Equation

A

A1 T1 + A2 T2 + A3 T3 / A1 +A2 + A3

112
Q

Heating Correction Factor Equation

A

Flow Temp + Return Temp / 2 - indoor temp

113
Q

Power Equation

A

P=IV

114
Q

Fan Power Equation

A

Pressure x flow rate

115
Q

Enthalpy Equation

A

Internal energy of system + (pressure x volume of system)

116
Q

Duct Size Equation

A

Volume flow rate = velocity x cross sectional area

117
Q

Heating Equation

A

Fabric + Ventilation + Infiltration - solar - internal

Losses 3 Gain 2