EMP EMP Building Systems & HVAC Optimization 2 — Questions and Answers
Question 1: What is 'thermal mass' in building energy management?
- The weight rating of HVAC equipment
- A building material's ability to absorb, store, and release heat energy (Correct answer)
- The temperature differential between inside and outside a building
- The total heating load of a facility
Correct answer: A building material's ability to absorb, store, and release heat energy
Thermal mass materials (concrete, masonry) store solar and internal heat gains during the day and release them slowly, reducing peak HVAC loads and shifting energy demand.
Question 2: In building energy analysis, what does a 'degree day' represent?
- A day when outdoor temperature exceeds 100°F
- A measure of how much and for how long outdoor temperature deviates from a base temperature (Correct answer)
- The maximum temperature differential in one day
- A unit of solar radiation intensity
Correct answer: A measure of how much and for how long outdoor temperature deviates from a base temperature
Heating or cooling degree days quantify the cumulative temperature deviation from a base (typically 65°F), serving as a proxy for building heating or cooling energy demand.
Question 3: What is the purpose of an Air Handling Unit (AHU) in a commercial building HVAC system?
- To generate chilled water for the cooling distribution system
- To condition and distribute air throughout the building by heating, cooling, and filtering (Correct answer)
- To control refrigerant flow between the compressor and evaporator
- To recover waste heat from boiler exhaust
Correct answer: To condition and distribute air throughout the building by heating, cooling, and filtering
An AHU conditions supply air by heating, cooling, humidifying, dehumidifying, and filtering it before distributing it to occupied zones through ductwork.
Question 4: Which insulation property determines how well a material resists heat flow, commonly used to rate wall and attic insulation in the US?
- U-value
- R-value (Correct answer)
- K-factor
- Emissivity coefficient
Correct answer: R-value
R-value measures thermal resistance per unit area; higher R-values indicate better insulating performance and are used in US building codes and energy standards.
Question 5: What is 'demand-controlled ventilation' (DCV) and why does it save energy?
- A method that increases airflow during peak occupancy to reduce energy rebates
- A system using COâ‚‚ sensors to modulate outdoor air intake based on actual occupancy (Correct answer)
- A strategy that pre-cools buildings before peak utility demand periods
- An approach that cycles HVAC systems on and off based on thermostat demand
Correct answer: A system using COâ‚‚ sensors to modulate outdoor air intake based on actual occupancy
DCV uses COâ‚‚ sensors as a proxy for occupancy, reducing outdoor air ventilation when spaces are less occupied and avoiding energy waste conditioning unnecessary outside air.
Question 6: ASHRAE Standard 90.1 is primarily used as:
- A certification standard for HVAC technicians
- The energy efficiency standard for commercial buildings adopted by most US building codes (Correct answer)
- A guideline for indoor air quality and ventilation rates
- A protocol for measuring and verifying energy savings
Correct answer: The energy efficiency standard for commercial buildings adopted by most US building codes
ASHRAE 90.1 establishes minimum energy performance requirements for commercial buildings and is referenced in the International Energy Conservation Code (IECC) and state energy codes.
EMP EMP Building Systems & HVAC Optimization 2
What is 'thermal mass' in building energy management?