Black book (#1)

  • Created by: TomK4
  • Created on: 09-04-18 14:35
Define 'Indoor Air Temperature, T(ai)'
The dry bulb temperature of the air in the space
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Define 'Mean Radiant Temperature, T(r)'
The uniform surface temp of a radiantly black enclosure in which an occupant would exchange the same amount of radiant heat as in the actual non-uniform space. [Average surface temperature weighted by surface area]
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Define 'Dry Bulb Temperature, T(db)'
Temperature of air measured by a thermometer freely exposed to the air, but shielded from radiation and moisture.
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Define 'Operative Temperature, T(c)'
Combines the air temp and mean radiant temp into a single value to express their joint effect
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What are factors affecting thermal comfort?
Radiant and air temperatures, air velocity, relative humidity, clothing, metabolic heat, acclimatisation, state of health, expectations, and even access to food and drink.
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What is 'PMV'?
PMV = Predicted Mean Votes. It combines the influence of air temp, mean radiant temp, air movement and humidity with that of clothing and activity level into one value. It is a scale that runs from Cold (-3) to Hot (+3).
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What is 'PPD'?
PPD = Predicted Percentage Dissatisfied. It is a function of PMV, given that as PMV moves further from 0, or neutral, PPD increases.
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What is 'Stack Ventilation'?
Bouyant warm air rises upwards and exits through 1+ high-level opening. Air displaced from the building causes cooler fresh air to be drawn into the building through low-level openings.
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What is a 'Partially Centralised Air/Water AC System'?
The bulk of the heating or cooling is carried within the occupied space by individual room units, such as fan coil units. These are supplied with hot or chilled water from a central plant via a pipework system.
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What is a 'Variable Air Volume (VAV)' system?
Air is supplied at a constant temp from central plant to one or more VAV unit in each zone. The unit contains a thermostatically controlled damper which regulates the amount of air entering the zone.
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What is a fan coil unit?
Typical unit comprises of a fan, heating coil, cooling coil and air filter. Fan draws a combination of room and fresh air through the filter and across the heating and cooling coils. The air passes into a plenum and distributed by ceiling diffusers.
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What are the RIBA 8 stages of Plan of Work (2013)?
0) Strategic Definition; 1) Preparation and Brief; 2) Concept Design; 3) Developed Design; 4) Technical Design; 5) Construction; 6) Handover and Close Out; 7) In Use.
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According to CIBSE TM52, what are the 3 criteria by which a building can be classed as overheating?
If a room or building fails 2/3 of: 1) Set limit of hours that op temp can exceed comfort temp by 1K+; 2) Severity of overheating within any one day; 3) Sets absolute max daily temp for a room
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What is the measurement of noise in buildings?
Noise Rating (NR) - Measurement of sound pressure (dB) taken at different Frequencies (Hz) can be mapped onto NR Curve Graph and highest NR is used.
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What is a Direct Digital Control System (DDC)?
Microprocessor-based with analogue inputs from sensors that are digitised. Primary units are for plant control and secondary units are for use in terminal units (e.g. fan coils). Can network controller together for exchange of info.
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What is a Building Management System (BMS)?
Essentially a networked Direct Digital Control System which has at least one permanent operator terminal, which is a user interface capable of a wide range of functions. Performs overall control and monitoring function of plant and systems.
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What is an Integrated Control System?
Building control systems are combined to allow display of multiple networks at a common point. Examples include: BMS, lighting, fire, security etc.
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What is the criteria for Building Reg L2A?
1) BER is not greater than TER; 2) Performance of fabric elements and building services achieve set standards; 3) Solar gains are limited; 4) Performance of building is consistent with BER; 5) Necessary provisions of energy efficient operation
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What is a condensing boiler?
A boiler that offers higher energy efficiency by recovering heat from the flue gases.
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What are minimum control packages?
A package of controls specific to each technology that represents the recommended min provision necessary to meet Building Regs Energy Efficiency requirements.
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How is COP calculated?
COP=Heat Output/Power Input
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What is SEER?
Seasonal Energy Efficiency Ratio - The total amount of cooling energy provided divided by the total energy input to a single cooling unit, summed over the year.
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What is SFP?
Specific Fan Power - Sum of design circuit-watts of fans that supply and extract air, including losses through switchgear and controls, divided by design air flow rate (units = W/l/s)
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What is a Daylit Space?
Any space within 6m of a window (provided the glazed area is at least 20% of the internal area of the wall) and areas below rooflights (provided the area is at least 10% of the floor area).
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What is a 'hard' bend in ductwork?
Bend in the plane of the longer side of the cross section
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What are the 3 common ductwork sections?
Rectangular, circular and flat oval (others available for special cases)
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For rectangular ductwork, what are the 3 drawbacks of high aspect ratios?
Increased pressure loss, heat gains/losses and overall cost
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What is an approximate equation for duct cross sectional area based on ACH (CIBSE Guide B)?
=>(Zone volume * ACH)/(3600 * velocity)
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What is the max cross sectional aspect ratio rectangular ductwork?
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What are installation effects in ductwork?
Poor inlet and outlet conditions which can cause poor fan performance and hence inefficient operation
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What are 3 measures to reduce 'installation effects' at the fan inlet in a duct?
1) Ensure that air enters axial fans without spin by improved inlet design or by installing a splitter. 2) Include turning vanes where there is a duct bend close to fan inlet. 3) Include a transition piece where the duct size reduces.
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What are 3 measures to reduce 'installation effects' at the fan outlet in a duct?
1) Ensure a min of two diameters of straight duct. 2) Where bends are close to the outlet, ensure radius bends with splitters are used. 3) Axial and propeller fans should preferably be fitted with guide vanes to provide energy recovery
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What is commissioning?
The advancement of a fixed building service after all or part of the system has been installed, replaced or altered. The system is taken from a state of static completion to working order.
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What does commissioning include for each system?
1) Setting to work; 2) Regulation (testing and adjusting); 3) calibration, setting up and testing of associated controls; 4) Recording of system settings and test results
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What 3 things should be found in a commissioning specification?
1) A description of various parties' responsibilities; 2) Pre-commissioning procedures; 3) On-site procedures; 4) arrangements for management of delays; 5) phased completion requirements; 6) requirements for witness testing; 7) system documentation
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What is a 'Certificate of Readiness for Employer (COR)'?
A series of documents that gather together all of the submittal data, test reports, snag lists etc. and present them in such a way as to show that a particular system is complete and ready to be set to work as designed.
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What is the objective of witnessing commissioning tests?
To formally witness, on behalf of the client, the degree to which the requirements of the commissioning specification have been met
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What are 3 witnessing duties?
1) Be satisfied that the requirements of the commissioning specification and the appropriate codes have been met; 2) check the flow rate at any selected flow measurement point; 3) check performance of all plant and systems
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What are two major effects of disturbances to flow arising from obstructions in ducts?
1) Eddies can be significantly larger in size and their velocities much higher than typical; 2) Flow velocities across the duct become asymmetrical (higher velocities can occur in part of the duct whilst reverse flow may occur in other parts)
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What will happen if a duct bend is too tight (r/w < 1)?
Flow will readily separate from the inside surface with subsequent eddying and increased pressure loss
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What is the recommended radius/width ratio for radiused bends for typical pressure loss and low pressure loss?
Typical = 1.5; Low pressure low = 2.0
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What are splitter bends in ductwork?
Tight radiused bends which use internal splitters to improve air flow
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What are mitred elbows in ductwork?
Rectangular duct bends
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When should mitred elbows have turning vanes? (> x mm)
When either dimension is greater than 200mm
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Other cards in this set

Card 2


Define 'Mean Radiant Temperature, T(r)'


The uniform surface temp of a radiantly black enclosure in which an occupant would exchange the same amount of radiant heat as in the actual non-uniform space. [Average surface temperature weighted by surface area]

Card 3


Define 'Dry Bulb Temperature, T(db)'


Preview of the front of card 3

Card 4


Define 'Operative Temperature, T(c)'


Preview of the front of card 4

Card 5


What are factors affecting thermal comfort?


Preview of the front of card 5
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