Answer

Mechanical and Electrical system in Architecture

Multiple Choice Questions

1. Define the following terms in HVAC

1. A damper is defined as a movable plate that regulates and redirects the airflow towards specific zones in the building/home.
2. A diffuser is a device used to ventilate by delivering conditioned air in an area. The device works through mixing the air indoors and managing the output of air by reducing the velocity and increasing the static pressure of the air duct.
3. An air handling unit is a component that regulates and circulates air in an HVAC system. it consists of a blower, cooling or heating elements, dampers, sound attenuators, and chambers or racks.
4. Return air is the air that is returned to the HVAC after circulation through the building. The air undergoes further condition and recirculation hence reducing the amount of energy used as in cases of only fresh air sources.

1. Define

1. Heat loss is the loss of heat through the building fabric when the internal temperature is higher than the outside temperature. Heat loss occurs through openings such as inefficient windows and doors, the roof and floors, and the external walls.
2. Heat gain is the increase in temperature due to solar radiation, long-wave infrared radiation, and heating from other sources within the building like computers, lights, mechanical systems, people, ovens, and heating appliances to name a few.

1. Define the following in plumbing systems

1. Pipes are long, hollow, and round tubes through which fluids (liquid or gas) flows. In plumbing, pipes are interconnected to create a piping system through which fluids can flow without damaging the building. Pipes can be made of metal, plastic, or concrete.
2. Fittings are components used to connect straight sections of a tube or pipe, regulate fluid flow, and adapt to varying shapes and sizes to manipulate and convey liquid waste, gas, or water within a piping system in buildings.
3. Fixtures are parts attached to a piping system and are used to carry or drain water through the building. Fixtures include components such as faucets, toilets, or sinks.
4. Valves are types of fitting that allow for direction, control, and regulation of fluids that pass through the pipe. They are commonly used to adjust system water pressure, prevent backflow, shut off water access, and direct fluid flow through the system

1. There are several ways of classifying buildings including mass classification. By considering mass content, buildings are classified as

1. Fire resistive buildings- these are constructed using concrete and protected steal in order to hold fire. They comprise stout and highly raised industrial and residential buildings.
2. Non-combustible buildings- these are new or refurbished models of commercial structures whose roofs and walls are made of non-combustible materials but are not fire-resistant.

1. Differentiate between thermal conductivity and thermal conductance

• Thermal conductivity describes the rate of steady heat flow through a unit area of a homogenous material induced by a unit gradient in temperature in a perpendicular direction to the unit area. The SI unit is W/mK.
• Thermal conductance is the rate of time steady heat flows through a unit area of a construction/material due to a unit difference in temperature between the body surfaces. Its SI unit is W/m²K.

1. Which of the following consumes more energy in a typical residence?

1. Space heating- Consumes the most energy in a typical residence
2. Space cooling
3. Water heating
4. lighting

1. Which of the following materials has the highest embodied energy?

12. Glass (12.7) is the highest
13. Cement (5.6)
14. Brick (3)
15. Aggregates (0.083)

1. In water tube boilers

1. The flames and hot gases pass through tubes that are surrounded by water (Correct)
2. Flames and hot gases pass through tubes that are surrounded by flames
3. Forced circulation takes place
4. All of the above

1. In a vapor compression system, what are the functions of the following components?

1. Evaporator- The evaporator acts as a heat exchange mechanism where the liquid refrigerant is vaporized at low temperature and pressure.
2. Compressor: The compressor has two main functions. The first one is to remove the vaporized refrigerant from the evaporator while maintaining the desired temperature and pressure. The second function is to increase the temperature and pressure of the refrigerant vapor through the compression process.
3. Expansion valve- The expansion valve serves to reduce the liquid refrigerant’s pressure. It also regulates the refrigerant flow into the evaporator.
4. Refrigerant- The refrigerant acts as a heat sink. It absorbs and rejects heat at low and high temperatures respectively.

1. Dry bulb temperature scale is located along the curved upper portion of the psychometric chart

1. True
2. False (Correct. It is on the lower; x-axis portion)

1. Moist air at standard conditions is at dry bulb temperature of 90 degrees F and wet bulb temperature of 60 degrees F. Use the psychometric chart to find:

28. Relative humidity= 28.7%
29. Dew point temperature= 35 degrees F
30. Humidity ratio= 30g/pound
31. Specific volume= 14.5 ft³/lb
32. Enthalpy= 25.4 BTU/lb