Design a Net-Zero House with AI: Durham, NC
Sample project
Prompts
The following are the prompts used to generate a house and AI reasoning returned at each round:
Round 1
Prompt:
Generate a colonial style house in Durham, North Carolina.
AI reasoning:
The user requested a colonial style house in Durham, NC. A colonial house has four walls, each 5 m high, forming a 10×12 m rectangular footprint. We center the foundation at [0,0]. The south wall faces negative Y, east wall faces +X, north wall faces +Y, west wall faces –X. We add a gable roof over the south wall with a 2.4 m rise. A single door (1.6×2.5 m) is centered on the south wall; to avoid overlap we omit the window pair at the door center. Each wall receives vertical pairs of windows (size 1.2×1.5 m) at 1.75 m and 3.75 m above ground, repeated every 4 m along its length, skipping the center on the south side because of the door. All materials use default R-values and air-permeability. Durham, NC is at latitude 35.9940, longitude –78.8986. Default time and lighting conditions were used.
Round 2
Prompt:
Add more solar panels so that they cover 90% of the south-facing roof.
AI reasoning:
To cover 90% of the south‐facing slope of the gable roof, we calculate the roof segment’s dimensions: 10 m along the eave and a 6 m horizontal run (rise 2.4 m), giving a slope length of ≈6.464 m. Ninety percent coverage implies a panel array of 9 m by 5.8176 m. We place a single solar panel element of that size at the segment’s center (plan center at [0,–3] m, elevation 6.2 m) on roof-1.
Round 3
Prompt:
Increase insulation of walls, roofs, and floor to reduce energy use.
AI reasoning:
To improve overall thermal performance, I increased the floor (foundation) insulation to R-6, wall insulation to R-5, and roof insulation to R-8 (m²·℃/W). These values reflect high‐performance assemblies that significantly reduce heating and cooling loads in Durham’s climate.
Round 4
Prompt:
Reduce U-values of windows to improve energy efficiency.
AI reasoning:
Improved window thermal performance by reducing all window U‐values from 2 W/m²·℃ to 0.8 W/m²·℃, typical of high‐performance triple‐glazed assemblies. This will significantly lower heat transfer while retaining original placement and size.
Round 5
Prompt:
Reduce the SHGC of windows to improve energy efficiency. Cover 90% of the north-facing roof with solar panels and rotate the house by 45 degrees.
AI reasoning:
To reduce solar heat gain, I decreased all window SHGC to 0.3, raising their opacity to 0.7. I added a matching solar panel array on the north‐facing roof to cover 90% of its slope, and rotated the entire house 45° around its center.
Round 6
Prompt:
Is there anything else we can do to further cut the energy use of the house?
AI reasoning:
Beyond high‐performance insulation, windows, and solar arrays, additional measures can further slash energy use:
1. Upgrade the air‐source heat pump’s efficiency by increasing the AC COP from 4 to 5.
2. Replace the entry door with a tighter, high‐performance model (U‐value reduced from 1.0 to 0.6 W/m²·℃).
3. Install a battery storage system to capture excess solar generation and smooth loads.
4. Add operable shutters on the south‐facing windows to block unwanted summer heat when needed.
These changes boost on‐site renewables, improve HVAC performance, and reduce envelope losses.
Round 7
Prompt:
Is there anything else we can do to further cut the energy use of the house?
AI reasoning:
Further energy reductions can be achieved by maximizing passive solar control and envelope performance: 1) Extend eaves to fully shade summer sun—set a 1 m overhang on the south wall and 0.5 m on the others. 2) Use a highly reflective roof surface (white finish) to reject solar heat. 3) Add exterior shutters on all windows for seasonal blocking of unwanted solar gains. These changes reduce cooling loads while maintaining winter daylighting.
Round 8
Prompt:
Is there anything else we can do to further cut the energy use of the house?
AI reasoning:
To push toward near‐zero loads, I upgraded to a ground‐source heat pump (COP 6), boosted insulation to Passive House levels (foundation R‐8, walls R‐8, roof R‐12), and specified ultra-low U-value glazing and doors (0.5 W/m²·℃). These envelope and system enhancements slash conduction losses and reduce HVAC demand to minimal levels.