Environmental and Energy Considerations
Environmental and Energy Considerations tests how a building's design, fuel choice and operation affect energy use, carbon emissions and comfort. Expect BER, primary energy, renewable options, orientation and overshadowing.
Core rules
- BER rates a dwelling from A to G using primary energy and CO2 indicators, not just the annual fuel bill.
- Primary energy includes conversion losses; electricity has a primary-energy factor above 1.
- Embodied energy is the energy in making and transporting materials; operational energy is used in the building.
- Passive design uses orientation, glazing, shading, insulation and airtightness before adding technology.
- Renewables include solar thermal, PV, heat pumps and biomass, each with site and maintenance limits.
Worked example
A south-facing roof has 30 m² of PV at 15% efficiency. Annual solar irradiance is 1,000 kWh/m². Ideal output = 30 × 1,000 × 0.15 = 4,500 kWh/yr. At 80% system efficiency, useful output ≈ 3,600 kWh/yr. The reasoning is: area × irradiance × efficiency × system efficiency. The result is an estimate, not a guaranteed bill saving.
Traps
- Treating BER as the same thing as energy bills.
- Ignoring overshadowing, orientation or roof pitch.
- Claiming a renewable system makes insulation unnecessary.
- Confusing embodied energy with operational energy.
State the indicator and the assumption behind any estimate.