WorksheetsResearch on Air Conditioning in Buildings
Total questions: 1
Worksheet time: 31mins
What is the primary function of an air conditioning (AC) system?
To heat a building
To cool a building
To control the humidity of the air
All of the above
Why is air conditioning provided in buildings?
To maintain an environment conducive to the health and wellbeing of the inhabitants
To increase the oxygen levels to dangerous levels
To make the air dry and uncomfortable
To add more CO2 and odours to the air
What does 'conditioned' air supply?
Excessive oxygen
Adequate oxygen, comfortable temperature, and removal of CO2 and odours
High levels of CO2 and odours
Only heating
In central plant AC systems, how is the air conditioned before being distributed?
By individual room units
By a central unit before distribution via ducting
By portable air conditioners
By window air conditioners
What is the effect of conditioning air in central plant AC systems?
The effect will vary in different parts of the building
The effect will be identical throughout the building
The effect will be stronger near the central unit
The effect will be weaker near the central unit
How can the effect of air conditioning be changed in central plant AC systems?
By adjusting the room thermostat
By changing the off-coil temperature
By opening windows
By using fans
What is the purpose of the preheater battery in the winter cycle?
To cool the air to 7ºC
To mix room air with fresh air
To heat fresh air to 7ºC and prevent filters from freezing
To dehumidify the air
What percentage of room air can be mixed with fresh air using the recirculation duct?
10%
25%
50%
75%
What is the 'duty' of a supply fan?
The temperature of the air it cools
The volume and static pressure of the air it operates
The percentage of fresh air it mixes
The amount of moisture it removes
How is air cooled in the cooling coil?
By heating it to 34ºC
By mixing it with fresh air
Using chilled water or a refrigerant gas
By increasing the static pressure
What is the purpose of the reheater battery?
To cool the air to 7ºC
To heat the air to 34ºC for comfort and compensate for heat loss
To mix room air with fresh air
To remove moisture from the air
What does CAV stand for in the context of air systems?
Constant Air Volume
Controlled Air Ventilation
Continuous Air Vent
Central Air Valve
What is the main advantage of a VAV system?
It can meet the comfort requirements of different zones in a building without heating and cooling at the same time.
It provides a constant temperature in all zones.
It reduces the need for air handling units.
It eliminates the need for air ducts.
In a VAV system, what does the air handling unit (AHU) do?
Dumps dirty air or recycles clean air
Increases the air temperature
Reduces the air flow
Filters out pollutants
How does a VAV system differ from a CAV system in terms of air flow?
VAV systems supply air at varying volumes, while CAV systems supply regular air flow at varying temperatures.
VAV systems supply regular air flow at constant temperatures, while CAV systems supply air at varying volumes.
VAV systems do not use air ducts, while CAV systems do.
VAV systems are used only for heating, while CAV systems are used only for cooling.
What does a VAV system do at the terminal unit to condition a room?
It changes the temperature of the air.
It changes the humidity of the air.
It adjusts the supply volume of air.
It filters the air.
What component in the VAV system is responsible for recirculating air?
Preheater
Recirculation damper
Silencer
Frost coil
Which component in the VAV system is used to reduce noise?
Silencer
Fan
Heater
Filter
What does AHU stand for in the context of building services engineering?
Air Handling Unit
Air Heating Unit
Air Humidifying Unit
Air Hydraulic Unit
Which component in the VAV air handling unit is responsible for cooling the air?
Reheater battery
Cooling coil
Centrifugal fan
Filter
In a VAV air handling unit, what is the function of the centrifugal fan?
To cool the air
To filter the air
To circulate the air
To reheat the air
Which component in the VAV air handling unit is used to reheat the air?
Cooling coil
Filter
Centrifugal fan
Reheater battery
What is the primary function of the filter in a VAV air handling unit?
To cool the air
To reheat the air
To clean the air
To circulate the air
What is the function of the velocity sensor in a VAV terminal unit?
To eliminate the velocity noise of the air flow
To adjust the volume of air entering the space
To reduce the velocity of air entering the space
To incorporate an optional reheater battery
What does an attenuator do in a VAV terminal unit?
Adjusts the volume of air entering the space
Eliminates the velocity noise of the air flow
Measures the temperature of the air
Controls the humidity of the air
What additional feature can be incorporated into a VAV terminal unit if necessary?
Velocity sensor
Volume control damper
Reheater battery
Attenuator casing
What is the typical constant air temperature maintained by VAV systems?
10°C
13°C
15°C
18°C
What component is used to feed air to each room in a VAV system?
Actuator
Thermostat
Diffuser
Reheater
What is the function of the actuator and damper in a VAV terminal?
To measure the temperature
To regulate the system
To boost the temperature
To control the airflow speed
What is the purpose of the reheater in a VAV terminal?
To cool the air
To measure the airflow
To boost the temperature
To regulate the system
What do pressure sensors link to in order to regulate the speeds of the induction motor blower fans?
Thermostats
Diffusers
Variable speed drives/variable frequency drives
Reheaters
What is the primary function of AC induction systems in buildings?
To cool the air to a single condition
To condition the air to a single condition
To heat the air to a single condition
To humidify the air to a single condition
What is a characteristic feature of room induction units in AC induction systems?
They have multiple return air ductworks
They are box-like casings with ports for high velocity air
They are spherical casings with ports for low velocity air
They have no ports for air passage
What happens to the room air in AC induction systems?
It is expelled outside
It is mixed with fresh, conditioned air
It is recirculated without mixing
It is cooled without conditioning
Why is there no return air ductwork in AC induction systems?
Because all recirculation takes place within the casing
Because the air is expelled outside
Because the air is not recirculated
Because the air is only heated
What is a significant drawback of using heating water to reheat the mixed air in AC induction systems?
It decreases the efficiency of the system
It significantly increases the capital cost of the system
It reduces the air quality
It requires additional ductwork
What is the primary purpose of using the Venturi effect in induction systems?
To increase fluid pressure and decrease velocity
To reduce fluid pressure and increase velocity
To maintain constant fluid pressure and velocity
To decrease fluid pressure and velocity
What is created as a result of the Venturi effect in induction systems?
Increased fluid pressure
Decreased fluid velocity
A vacuum that recirculates air
A constant fluid flow
What is the primary function of a dual duct system in building services engineering?
To distribute air via a single duct
To distribute air via two ducts: one for chilled air and one for heated air
To distribute air via three ducts: one for chilled air, one for heated air, and one for ambient air
To distribute air via a single duct with multiple temperature zones
What is the purpose of insulating the two ducts in a dual duct system?
To prevent noise from escaping
To prevent the chilled air from absorbing warmer ambient temperatures and the heated air from losing heat to the surrounding air
To increase the speed of air flow
To reduce the cost of the system
What happens to the incoming fresh air before it enters the fan suction chamber in a dual duct system?
It is split into hot and cold air
It is preconditioned
It is filtered
It is humidified
What is the function of terminal boxes in a dual duct system?
To filter the air before it enters the room
To mix chilled and heated air before discharging it into the room
To exhaust air out of the building
To control the temperature of the return air
What are compression cycle refrigeration circuits known as?
Variable refrigerant volume (VRV) systems
Variable refrigerant flow (VRF) systems
Variable air volume (VAV) systems
Variable air flow (VAF) systems
Where are VRV systems typically used?
Where ductwork is possible
Where ductwork is not possible or needed
In large open spaces
In outdoor environments
How is the main refrigeration unit in a VRV system typically sized?
To feed multiple storeys of a building
To feed a single storey of a building
To feed an entire building
To feed only individual rooms
How many pipes does a VRV system's distribution system have?
One
Two
Three
Four
What capability do individual room units in a VRV system have?
They can only cool the room
They can only heat the room
They can reverse the flow of refrigerant to heat or cool the room
They can only ventilate the room
What system do room units have to remove condensate when cooling?
A heating system
A ventilation system
A drainage system
A filtration system
What does a single outdoor condensing unit connect to in a VRV system?
Thermostats
Air handlers
Refrigerant
Heat source
What is cycled through the outdoor unit in a VRV system?
Water
Air
Refrigerant
Electricity
What allows heating and cooling to occur at the same time in different rooms in a VRV system?
Condensing unit
Air handlers
Thermostat
Heat source
What is one advantage of VRV systems compared to forced air systems?
Higher energy consumption
Requires a back-up heat source
Minimal energy loss
More complex installation
What is the primary function of split system air conditioners?
To heat the room
To condition individual rooms as stand-alone units
To provide ventilation
To humidify the air
What is the role of the evaporator in a split system air conditioner?
To draw outside air across the heat exchanger
To remove heat from the refrigerant gas
To evaporate the refrigerant liquid and remove heat from the room air
To compress the refrigerant gas
Which component of the split system air conditioner is located externally?
Evaporator
Compressor
Condenser
Expansion valve
What type of tubing is used to connect the two units of a split system air conditioner?
Aluminum tubing
Plastic tubing
Copper tubing
Steel tubing
What is the function of the propeller fan in the condenser unit?
To draw room air across the heat exchanger
To draw outside air across the heat exchanger
To compress the refrigerant gas
To evaporate the refrigerant liquid
