What is passive design, and how do you design an energy-efficient building?
Reduce demand first, then choose equipment
Energy efficiency is often thought of as efficient air conditioning, solar panels or automation. But the cheapest energy is the energy never used. Even the most efficient cooling system cannot make up for a large, unshaded, west-facing glass façade. The order is: first reduce the load through architecture, then meet the remaining demand with efficient systems, and finally add renewable energy.
Six principles
| Principle | What is done | Benefit |
|---|---|---|
| Orientation and massing | Long façades face north and south where possible; a compact form is preferred | Solar gain in winter, less overheating in summer |
| Insulation and airtightness | Walls, roof and floor are insulated; thermal bridges and air leaks are prevented | Heating and cooling loads fall markedly |
| Window design | Glazing ratio set by orientation; thermal and solar control glass selected | Daylight balanced against heat loss and gain |
| Shading | Horizontal elements on the south, vertical on the east and west; movable systems | Summer sun blocked, winter sun let in |
| Daylight | Room depth, window head height, light shelves and courtyards | Less need for artificial lighting during the day |
| Natural ventilation | Cross ventilation, stack effect, night cooling | No mechanical cooling needed in the shoulder seasons |
What changes across Türkiye's climate zones?
There is no single right solution. In cold climates, the priority is insulation, airtightness and using southern sun. In hot, humid coastal regions, shading and air movement come first. In hot, dry inland regions, thick walls with high thermal mass and night ventilation are effective. In mild, humid climates like Istanbul's, a balanced approach is needed: good insulation, a controlled glazing ratio and strong shading on the west façade. The Turkish standard TS 825 divides Türkiye into climate zones and sets insulation limits for each.
Passive design and mechanical systems
- As the load falls, equipment, ducts and plant rooms get smaller, reducing initial cost.
- Airtight buildings need heat-recovery ventilation for fresh air.
- Daylight sensors automate the savings from natural light.
- Decisions are verified with energy modelling and daylight analysis, not assumptions.
For façade material and system decisions, see our article on choosing façade materials.
Common mistakes
- Placing the building on the plot without considering orientation.
- Using the same windows and glass on every façade.
- Cutting shading elements first when the budget is reduced.
- Thickening the insulation without fixing thermal bridges and air leaks.