CASE49 · Buildings · Design-alternative simulation
Testing eighteen building-design variables against one virtual-office baseline
Single-variable model runs compare envelope, thermal mass, lighting, HVAC and plant choices under consistent assumptions. Results reveal both favorable and unfavorable annual energy-cost changes.
01 · CASE ANALYSIS
Design question
A virtual office baseline allows one variable to change while weather, schedules and other model assumptions remain fixed. The comparison identifies sensitivity rather than promising a universal saving.
Eighteen alternatives covered architectural, lighting, HVAC, plant, control and tariff variables.
02 · CASE ANALYSIS
Four initial comparisons
Wall insulation from 70 to 90 mm produced a near-zero cost change. Floor weight from 105 to 45 kg/m² increased cost by approximately 1.1%.
Lighting density from 30 to 10 W/m² reduced modeled cost from approximately KRW 3,114 million to KRW 2,550 million/year. A distributed chiller configuration reduced cost by approximately 1.6%.
| Variable | Change | Annual cost change |
|---|---|---|
| Wall insulation | 70 → 90 mm | Approximately +0.0%; +KRW 1 million |
| Floor weight | 105 → 45 kg/m² | +1.1%; +KRW 34 million |
| Lighting density | 30 → 10 W/m² | −18.1%; −KRW 564 million |
| Chiller arrangement | 4,300 RT × 1 → 2,800 / 1,200 / 800 RT combination | −1.6%; −KRW 50 million |
03 · CASE ANALYSIS
Interactions can reverse intuition
AHU heating supply temperature from 29 to 25°C increased modeled cost 5.9%; cooling supply temperature from 12 to 15°C increased it 2.3%. These results require examination of airflow, zone loads and plant interactions.
Daylighting reduced modeled cost by 14.3%, approximately KRW 445 million/year. Its lighting and cooling interactions differ from simply increasing glazing area.
04 · CASE ANALYSIS
Broader scenario portfolio
The source includes thermostat changes, economizer operation, glazing, curtains, outdoor-air conditions, pump variable speed, ice storage and chilled-water temperature. The reported outdoor-air input is 36 → 20 m³/person; its time basis is not supplied here and must be checked in the original model.
Run an integrated model for the selected measures. Independent scenario percentages cannot be added because their effects can overlap.
| Variable | Change | Cost change |
|---|---|---|
| Heating setpoint | 22 → 21°C | −0.3% |
| Cooling setpoint | 26 → 27°C | −0.6% |
| AHU heating outlet | 29 → 25°C | +5.9% |
| AHU cooling outlet | 12 → 15°C | +2.3% |
| Economizer | Disabled → enabled | −0.7% |
| Window ratio | 63% → 40% | −1.7% |
| Glazing SC | 0.33 → 0.75 | +9.3% |
| Curtains | None → 50% application | −1.0% |
| Electricity tariff | Option II → I | −0.8% |
| Outdoor-air input | 36 → 20 m³/person (source notation) | −2.4% |
| Pump variable-speed drive | Absent → present | −1.1% |
| Ice storage | Absent → present | −3.1% |
| Daylighting | Absent → present | −14.3% |
| Chilled-water outlet | 6.7 → 8°C | −0.3% |
05 · CASE ANALYSIS
Design decision and evidence
Check lighting service, indoor air quality, comfort, construction feasibility, investment and maintenance alongside modeled energy cost. A cost minimum is not automatically a feasible design.
These results belong to a virtual office, not an actual metered project. Changing a tariff can change cost without changing energy consumption.
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