Part 1: Building Envelope System Design
The building is oriented toward the south. The south facades mainly consist of curtain walls, and the other sides of the envelope are mostly brick walls. The WWR of the different sides of the building is as follows:
- North WWR: 32%
- East WWR: 24%
- South WWR: 73%
- West WWR: 35%
1. Curtain Walls
External walls facing south were mainly exterior glazing in order to allow lots of natural light into the rooms. The properties of the curtain panel are shown below. The glazing facades facing south and north are made of “low-E triple glazing SC=0.65”. Also, I added horizontal light shelves to help block the sun for the curtain walls.
- R-value: 3.9015 ft2·°F·h/BTU
- Thermal mass: 0.2563 BTU/(ft2·°F)
2.Brick Walls
For the brick walls, I used “Basic Wall Exterior - Brick on Mtl. Stud”.
- R-value: 54 ft2·°F·h/BTU
- Thermal mass: 7.1826 BTU/(ft2·°F)
This is a high-performing wall that I think looks quite nice to also provides a nice aesthetic effect.
3. Roofs
Some roofs have an insulated steel truss roof with a green roof on top, while the other roof is just an insulated steel truss with solar panels to be placed on top. The third floor’s roofs are designed to have a slope for better surface area for solar panels. Moreover, roofs are designed to have overhangs to allow for shading in the summer months while still allowing sunlight and heat into the buildings for the winter months.
Green roof: provides additional insulation to the building, reduces the urban heat island effect, and provides a high thermal mass value. The properties of the green roof are shown below:
- R-value: 2.068 ft2·°F·h/BTU
- Thermal mass: 20.2755 BTU/(ft2·°F)
Steel Truss- Insulation on Metal Deck - EPDM Roof: combines a steel truss structure, insulation layer, and a single-ply rubber membrane known as EPDM (ethylene propylene diene monomer). This type of material provides a durable and weather-resistant surface.
- R-value: 113.1719 ft2·°F·h/BTU
- Thermal mass: 2.0088 BTU/(ft2·°F)
4. Floors
For the ground floor, I used “Steel Bar Joist 14’’ -VCT on Concrete”.
- R-value: 82 ft2·°F·h/BTU.
- Thermal mass: 3.2444 BTU/(ft2·°F)
The ground floor can be a major source of heat loss. A high R-value can help to reduce the amount of heat that escapes from the building through the ground floor, which can result in significant energy savings.
For levels 2 and 3 floors, I used 8’’ Precast Concrete Slab.
- R-value of 17 ft2·°F·h/BTU
- Thermal mass: 2.0088 BTU/(ft2·°F)
Precast concrete has several advantages over cast-in-place concrete. It offers superior quality control due to being manufactured in a controlled factory environment, resulting in consistent quality and uniformity of the finished product. Precast elements can be installed quickly on the construction site, saving time and reducing labor costs. Moreover, the off-site production of precast elements can reduce the amount of noise, dust, and other disruptions that occur during on-site construction.
5. Windows
For all types of windows, I changed the glazing to a low-E triple glazing SC=0.65 glass (same as curtain wall).
For exhibit areas that do not have curtain walls, I used “48” x 72” Window - Casement - Double - Roundtop” to make it looks more artistic.
For most of the offices and conference rooms, I used simple fixed 36” x 72” windows.
For most restrooms and corridors, I used 85’’x60’’ Window-Casement-Triple-Middle-Transom.
6. Doors
For the two front entrance doors, I used 96’’x106’’ Door-Exterior-Revolving-Full Glass-Metal.
For the two front exit doors, I used 72’’x84’’ Door-Passage-Double-Flush.
For the two exit doors at the north side of the building, I used 56’’x68’’ Door-Curtain-Wall- Double-Storefront.
7. Shading
For the fixed windows, I put the light shelves 1’ below the top of the window allowing some light to bounce off the top of the light shelf and reflect up into the room. At the same time, also provides some nice diffuse daylight.
I sized these shelves using the sun path & shadows features in Revit, making sure the windows will be shaded during the hottest times of the year. Also, by the suggestion of Insight, the shades extend to about 2/3 of the window height.
Other shading features like roof overhangs and horizontal light shelves are mentioned above and are all used to prevent direct sunlight during noon time in summer.
Part 2: Energy Model
Baseline Scenario:
- Operating schedule factor: 12/5
- Plug Load Efficiency: 0.6 W/sf
- Lighting Efficiency: 0.3 W/sf
The resulting average EUI is 81.5 kBtu/sf/yr.
At the baseline scenario, the building is performing decently well at below the ASHRAE 90.1 but not low enough for the goals of my overall building energy consumption.
Then, I investigated the impact of building envelope-related design. The following are the parameters that I adjusted:
- WWR western walls: 35%-30%
- WWR eastern walls: 24%-15%
- WWR northern walls: 32%-30%
- WWR southern walls: 73%-65%
- Window glass north, east, and west: TrpLoE
- Window shades north, east, and west: 2/3 window height
- Wall construction: Current BIM material
- Roof construction: 10.25-inch SIP
The resulting average EUI is 57.5 kBtu/sf/yr.
I investigated further by also considering the impact of power and lighting. The following are the parameters that I adjusted:
- Plug load efficiency: 0.6 W/sf
- Lighting efficiency: 0.3 W/sf
- Daylighting and occupancy control
The resulting average EUI is reduced to 56.5 kBtu/sf/yr.
Some other factors that I adjusted:
- HVAC: High-Efficiency Heat Pump
- Inflitration: 0.17 ACH
- Building Orientation: Orientation of current BIM
The resulting average EUI is reduced to 37.4 kBtu/sf/yr.
Finally, I consider the benefits of adding PV panels:
- Surface Coverage: 90%
- Panel Efficiency: 20.4%
- Payback Limit: 30 years
The resulting average EUI is reduced to 9.27 kBtu/sf/yr.
EUI value continues to drop as I add more and more design improvements. The final EUI reduces to 9.27. The PV panels decrease this score the most substantially compared to modifications made by adjusting lighting, envelope-related design, and other factors. The figures below show the solar analysis and my PV panels layout.
Part 3: Daylight Analysis
Level 1:
Level 2:
Level 3:
On levels 1 and 2, there are some rooms with not enough lighting. Some of those are the mechanical rooms, restrooms, and storage rooms, so artificial lighting can be used there when needed. One of the exhibit rooms on level 1 is not getting enough daylight. Maybe bigger windows should be added to this room, or artificial lighting will have to be used.
There is a lot of sunlight in the front of the building since I am using a curtain wall for the semicircle. Other shading features should be added for example, a larger overhang of the roof and automated shading devices could be implemented there. The daylight on the third floor is perfect. The yellow part is the green roof, so it is fine to have extra light. Only the mechanical room has a red color, but it can rely on artificial lighting.