How well do BER ratings predict your home's actual energy performance?
Éire / Ireland
A study from ESRI investigates the accuracy of Irish Building Energy Rating (BER) scales in reflecting observed energy performance for home heating and heat loss. The context is set within Ireland's goal, outlined in the 2019 Climate Action Plan, to upgrade half a million homes to B2 BER scale by 2030 to combat climate change.
The BER scales, serving as benchmarks for energy efficiency, are utilized in the government's retrofit scheme with an €8 billion budget. These scales guide household investments by projecting energy performance based on standardized values. The accuracy of these projections becomes crucial for realizing benefits and meeting climate policy targets.
Two studies isolate building fabric performance by examining indoor temperature drop during heating system off-hours and variations in boiler operation during winter months. Using detailed data collected over two years from smart thermostats, the analysis reveals that improving energy efficiency, as indicated by BER scales, reduces energy use for heating and enhances heat retention. However, the observed differences are considerably lower than projected, indicating a discrepancy in the accuracy of BER scales in capturing insulative performance.
The implications extend to policy and homeowner decision-making. While upgrading energy efficiency remains beneficial, aligning investments with the 'B2' BER standard may lead to higher costs than necessary. The study suggests that a more accurate BER system, reflecting individual dwelling characteristics, could guide a cost-effective decarbonization trajectory. This also affects homeowners planning energy efficiency upgrades, emphasizing the need for a refined, data-driven approach to identify suitable upgrades tailored to specific dwelling characteristics.