Chapter 3 HVAC Load Estimating
TRUE/FALSE. Write ‘T’ if the statement is true and ‘F’ if the statement is false.
1) Manual load calculations should be considered only for preliminary design or simple buildings. 1) _______
2) ASHRAE methods have become increasingly precise and have become the basis for algorithms
in computer programs.
2) _______
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
3) Which of the following is true concerning accuracy in load calculations? Select all that apply. 3) _______
A) Is difficult due to schedule constraints during design
B) Relies on conservative assumptions
C) Has a significant effect of initial and operating costs
D) Is needed for proper equipment sizing
TRUE/FALSE. Write ‘T’ if the statement is true and ‘F’ if the statement is false.
4) Outdoor conditions are expressed as “% design.” A 99% outdoor criteria is a lower temperature
than a 99.6% criteria.
4) _______
5) A 1% criteria is a lower temperature than a 2% criteria. 5) _______
SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
6) A wall assembly has an overall resistance of R-10. What is its U-factor? 6)
_____________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
7) Air films have a significant resistance to heat flow. There are films on both the inside surface and
the outside surface of a wall. Which has the higher resistance?
7) _______
A) Outside film.
B) Inside film.
C) Neither; they’re the same.
SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
8) Identify which of these equations should be used for the following load estimates:
(1) Q = U × A × TETD (2) Q = U * A * TD (3) Q = 1.1 * CFM * TD
(4) Q = SC * A * SHGF (5) Q = 4.5 * CFM * ∆H (6) Q = 3.41 * P
A. ________ Conducted heating load through a roof
B. ________ Conducted cooling load through a wall
C. ________ Conducted cooling load through a window
D. ________ Solar cooling load through a window
E. ________ Winter infiltration load
F. ________ Summer infiltration load
G. ________ Appliance cooling load
8)
_____________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
9) If lighting is recessed in a return air plenum ceiling, what will the effect be on supply air needed
to cooling the occupied space?
9) _______
A) Less air will be needed.
B) More air will be needed.
C) Air requirement will be the same.
10) Building occupants are often assume to liberate 500 Btuh, consisting of 250 Btuh sensible heat +
250 Btuh latent heat. If, for some reason, the occupants liberated 600 Btuh, consisting of 150 Btuh
sensible heat + 450 Btuh latent heat, which of the following effects would occur? Select all that
apply.
10)
______
A) Less refrigeration would be needed.
B) More refrigeration would be needed.
C) More air would be needed to cool the space.
D) Less air would be needed to cool the space.
11) Central building air conditioning equipment is sized based on the peak coincident total air
conditioning load for the building, generally assumed to occur on July 21 for 40° N latitude.
About when is this load likely to occur for most buildings?
11)
______
A) 8:00 AM B) Noon C) 4:00 PM
12) If the building is designed to have separate air conditioning systems for each face (N, S, E, and
W), for what time of day would you size the East facing system?
12)
______
A) 8:00 AM B) Noon C) 4:00 PM
