Blog / ESG Bristol Building Roof Insulation and Triple-Glazed Roof Lights Fitted 1 April 2022 — by Barry Bassett We replaced the single-glazed roof lights with triple glazed (U-value 1.6) and sprayed foam insulation to the underside of the steel roof of our Bristol building to improve its thermal efficiency.These two initiatives are predicted to save 6.6T CO2 per year.