1. Analyzing the initial building model
Benchmark scenario:
Criterion | Value |
Operating Schedule | 12/5 |
Roof Construction | R38 |
Predicted Mean EUI | 60.9 kBtu/ft^2/yr |
This base model has just reached the ASHRAE 90.1 standard.
2. Building envelope-related design decisions impact
- Thermal Properties of Wall Surface (Wall Construction) for all orientations
- Glazing % (Window-to-Wall Ratio) for each orientation (North, South, East, West)
- Thermal Properties of Glazing Surfaces for each orientation
- Window Shading amount for each orientation
I have changed the criteria above from the benchmark scenario one by one. Below is a table for the EUI results under different assumptions. Blue cells indicate relatively significant factors, grayed-out cells bring negligent impacts to the model’s energy performance.
Criterion | Option |
Wall Construction | 12.25-inch SIP |
WWR Western | 0-15% |
WWR Eastern | 0-15% |
WWR Northern | 0-50% |
WWR Southern | 0-100% |
Glazing East | Trp LoE |
Glazing West | Trp LoE |
Glazing North | Trp LoE |
Glazing South | Dbl LoE, Sgl Clr, Dbl Clr, Trp LoE, BIM |
Shades East | 2/3 Win Height |
Shades West | 2/3 Win Height to no shading |
Shades North | 2/3 Win Height to no shading |
Shades South | 2/3 Win Height to no shading |
Predicted Mean EUI | 50.5 |
We have reached the target — under 54 kBtu per sqft per year.
3. Power and lighting impacts
The following criteria are used for the factor tiles related to power and lighting impacts:
- Plug Load Efficiency (the equipment and appliances that draw power)
- Lighting Efficiency (based on the efficiency of the lighting fixtures)
- Daylighting & Occupancy Controls
Criterion | Option |
Plug load efficiency | 1 W/sf |
Lighting Efficiency | 0.3 - 1 W/sf |
Daylighting & occupancy controls | Daylighting & occupancy controls |
Predicted EUI (based on Benchmark) | 49.2 |
Predicted EUI (based on Building Envelop changes) | 38.8 |
We drove the predicted mean EUI down to an even lower value. The range has also been lowered from changing the building envelope only.
4. Photovoltaic panel impacts
In this section, I changed the following criteria to explore the benefits from PV on top of the previous improvements.
- Surface Coverage
- Panel Efficiency
- Payback Limit (how many years you will allow for the panels to pay for themselves
Criterion | Option |
Surface Coverage | 75% |
Panel Efficiency | 20.4% |
Payback Limit | 20-30 years |
Predicted EUI (along with all other improvements) | 6.32 |
Surface coverage and payback limit significantly improved the energy performance. Then mean predicted EUI achieved the Architecture 2030 goal, and the range is a lot lower than without PV too.
Here is a screenshot of the final energy model imposed on the building (facing south). Through this exercise, I am convinced that wall insulation, window-to-wall ratio and glazing on large faces are very important when building the envelope. I have also realized that PV panel qualities are critical for building sustainability.
My final results are not energy-negative, but with more parameter-tweaking, net negative can be achieved. I have chosen my current my factor options based on a more balanced and common setting, for example, I made the roof covered with 75% of PV panels rather than 90%, since there might be other uses for the empty parcel.
