7) What is causing the second Sep clear graph to require cooling between 7 am to 10 am and 9 pm to midnight?

A) There aren't enough windows to cross vent.
B) The temperature outside is too hot.
C) Cross ventilation has been turned off in the Schedules on the second September.
D) The wind is blowing from due East and there aren't any windows on those elevations.


8) Comparing all September graphs, what causes the cooling peak to occur and what causes total cooling load (the length of the hour bars) to be different?

A) Sometimes the building is occupied and sometimes it isn't.
B) Cross ventilation is used to reduce the need for mechanical cooling.




9) Use the Exercise 5A building file as it was downloaded. Save as "(name) Ex 5 setback".





10) Set the schedule to look like this. Cross vent is on all four days. Set the maximum temperature to 90 degrees during the unoccupied times for day 1 and day 3. (First select the radio button next to maximum. Drag the first box up to 90, hold down the shift key and drag across). Close the
Schedules window.




11) Set the graph palette to Total Net Heat Flow and set the scale to 20,000 BTU. The evaluation days should all be set to Sep Clear. Calculate. Save.

Question

Please answer the following question using the graphic report:
(More than one answer may be correct, but extraneous answers will be considered incorrect. For example if two answers are correct, and you mark only one, the answer is incorrect. If you marked three, including the two correct answers, the answer is incorrect).



12) What are the differences between Sep graph 1 and Sep graph 3 that reduce the total net flow to almost zero in graph C?

A) A higher thermostat setting allows the building represented by graph 3 to cross vent most of the day.
B) The climates are different.
C) In graph 3, the occupants are absent.
D) In graph 3, the higher thermostat setting results in less heat transfer through the walls and roof.




13) Save the file as "(name) Ex 5 shade".

14) Open up the south window specification, and add external, roll down shades. Close the spec.

15) Change the schedule to look like this. Turn off both interior and exterior shading for days 2 and 4. Revert the maximum thermostat setting back to 78 degrees for days 1 and 3. Close the window.

16) Go to the graphic report and calculate. Save.

Questions

Please answer the following questions using the graphic report:
(More than one answer may be correct, but extraneous answers will be considered incorrect. For example if two answers are correct, and you mark only one, the answer is incorrect. If you marked three, including the two correct answers, the answer is incorrect).

17) Why does the building represented in graph 3 have the lowest net flow?

A) It has a higher thermostat setting.
B) It uses roll down shades.
C) It doesn't have any occupants.
D) It has more ventilating windows.




18) Using the "(name) Ex 5 shade" generated for question 16, change the climate days to March clear, June clear, September clear, and December clear. Run calculations.

Which of the following would improve the building's performance as measured by total net heat flow?

A) Reduce shading on the south glazing.
B) Raise the maximum thermostat setting when the building is unoccupied.
C) Lower the minimum thermostat setting when the building is unoccupied.
D) Increase R-value of the windows.

Comments:

When you finish the questions, press the button below to submit your answers.

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IMPORTANT: when you submit the questions for grading, you will be taken to Cooldown #5A. If you are not taken to the cooldown, there may have been an error in the automatic grading -- contact course personnel.