To design the HVAC system for the example building, I have considered the following steps.
Step 1: In the table below, I have taken note of the reported heating and cooling loads for each space and the calculated supply airflow reported for each of the spaces included in the space schedule. (Note that not all spaces are included in the schedule).
Space Name | Cooling Load (Btu/h) | Heating Load (Btu/h) | Cooling Airflow (CFM) | Heating Airflow (CFM) |
1 Office | 1,994.4 | 489.7 | 69 | 18 |
2 Office | 2,408.1 | 512.4 | 83 | 20 |
3 Office | 1,629.5 | 122.8 | 58 | 16 |
4 Hallway / Pathway | 13,282.0 | 1,942.1 | 412 | 373 |
6 Meeting Room | 24,754.9 | 8,260.1 | 758 | 287 |
7 Public Space | 25,372.7 | 8,911.8 | 803 | 310 |
9 Restroom | 1,679.1 | 363.0 | 58 | 19 |
10 Space | 6,956.8 | 601.0 | 243 | 27 |
11 Space | 8,693.4 | 615.8 | 304 | 34 |
12 Restroom | 1,644.3 | 355.7 | 57 | 19 |
15 Mechanical Room | 1,374.8 | 155.0 | 48 | 20 |
16 Conference Room | 23,099.3 | 7,035.0 | 682 | 245 |
17 Public Gathering | 17,143.1 | 161.6 | 601 | 127 |
18 Cafe | 44,630.1 | 7,318.6 | 1,387 | 306 |
19 Restroom | 1,331.7 | 313.8 | 44 | 19 |
20 Restroom | 1,298.2 | 205.2 | 45 | 19 |
21 Museum Display Room | 11,224.0 | 676.2 | 397 | 62 |
22 Hallway / Pathway | 4,546.6 | 1,819.8 | 134 | 152 |
Step 2: Then, I considered what the cooling and heating airflows are, highlighted in red the maximum value between the two, and estimated a reasonable (and higher) amount of airflow in CFM. This value will be used to design both the supply air diffusers and the return air diffusers.
I selected each airflow in a way that the sum is 8000 CFM, 2000CFM more than the total CFM
Space Name | Cooling Airflow (CFM) | Heating Airflow (CFM) | Selected Airflow (CFM) |
1 Office | 69 | 18 | 100 |
2 Office | 83 | 20 | 100 |
3 Office | 58 | 16 | 150 |
4 Hallway / Pathway | 412 | 373 | 600 |
6 Meeting Room | 758 | 287 | 900 |
7 Public Space | 803 | 310 | 1200 |
9 Restroom | 58 | 19 | 100 |
10 Space | 243 | 27 | 300 |
11 Space | 304 | 34 | 400 |
12 Restroom | 57 | 19 | 100 |
15 Mechanical Room | 48 | 20 | 100 |
16 Conference Room | 682 | 245 | 700 |
17 Public Gathering | 601 | 127 | 700 |
18 Cafe | 1,387 | 306 | 1650 |
19 Restroom | 44 | 19 | 100 |
20 Restroom | 45 | 19 | 100 |
21 Museum Display Room | 397 | 62 | 400 |
22 Hallway / Pathway | 134 | 152 | 300 |
What I have noticed from this table:
- Unusually high heating load in Meeting Room (6):
- The heating load in the Meeting Room is significantly higher than the other spaces, which might be unexpected. It could be due to specific activities or equipment in that room.
- Higher cooling airflow in the Cafe (18):
- The cooling airflow in the Cafe is notably high compared to other spaces. This could be reasonable if there are high occupancy or heat-generating equipment in this area.
- Unusually low heating load in the Public Gathering space (17):
- The heating load in the Public Gathering space is surprisingly low. This might be accurate based on the specific conditions of the space.
Step 3: given the table above, I started placing the air diffusers accordingly. Then I started modeling the air ducts, using recatngular 12x12 air ducts types. I provided two separate supply branches on each floor level, one for the West zone and one for the East zone, and I routed each supply branch back to the mechanical room on that floor level.
Step 4: I connected each duct with the air diffusers (supply and return) using flexible ducts.
Mechanical Floor Plans
Floor 0:
Floor 1:
Note: ducts and diffusers were added on floor 1 in conjunction with the stairs location, but not on floor 0 due to the actual presence of stairs at the ceiling level.
Interior Views
On of the main challenges I have encountered during the HVAC layouting was ensuring that the ducts did not obstruct critical areas like elevators and stairs. I accidentally covered the stairs on the floor zero and I had to rework in a later stage to remove the ducts and air suppliers from there.
Additionally, I have noticed that there any conflicts between my structural system and my mechanical systems, like shown in the image below.
Also, supply duct routing was challenging in terms of understanding where to place the airflows correctly so that to avoid the intersection of air ducts for return and supply air.
Finally, I would place a ceiling to conceal the structural and mechanical systems right below the lowest element (in my case, the return air ducts), at a heights of 8’ (at level of the air diffusers). This ensures that the design not only enhances the visual appeal but also maintains optimal functionality, as 8’ is a good height for a small building like the one of this assignment.