Deep Retrofits Set New Sustainability Bar in UK
A series of large-scale UK retrofits are establishing new benchmarks for sustainable building transformation by retaining existing structures while upgrading for wellness and energy efficiency. Projects like Piercy & Co's 1 Appold Street, which keeps 75% of its original structure, and the Exchange House in London are integrating WELL standards and biodiversity into commercial upgrades. The residential Bowmans Lea EnerPHit project further models this trend by using natural materials for a whole-house energy upgrade.
- The WELL Building Standard's Light concept establishes thresholds for circadian lighting design using a metric called Equivalent Melanopic Lux (EML). To support occupants' circadian rhythms, it requires light levels of at least 150 EML for a minimum of four hours per day, measured on the vertical plane at eye level. For evening, it recommends a maximum of 10 lux of melanopic equivalent daylight illuminance (m-EDI) starting at least 3 hours before bedtime. - The residential Bowmans Lea project is the UK's first certified step-by-step EnerPHit retrofit, a standard for phased deep energy upgrades equivalent to Passivhaus for existing buildings. The first phase of the owner-architect-led project, which included window upgrades and insulation using natural materials like cork, reduced space heat demand by 53%. - The 1 Appold Street project targets top-tier certifications including BREEAM Outstanding, WELL Platinum, and a NABERS 5.5-star rating, reflecting a comprehensive approach to sustainability and occupant wellbeing in its design. This deep retrofit goes beyond energy to holistically address factors like indoor air quality, water, and materials. - Digital Addressable Lighting Interface (DALI) is a bi-directional protocol enabling individual and group control of luminaires, as well as status monitoring. DALI systems can integrate with building automation systems and sensors for daylight harvesting or occupancy detection, which can reduce lighting-related energy costs by up to 60% or more. The newer DALI+ standard combines this control with wireless and IP-based networking for greater installation flexibility. - A circular economy approach to luminaire design prioritizes modularity, reparability, and the use of recyclable materials to extend product lifecycles and minimize waste. This "cradle-to-cradle" thinking involves designing for disassembly, allowing components like LED modules and drivers to be easily replaced or upgraded, which contrasts with the traditional linear "produce, use, dispose" model. - In deep retrofits, a "fabric-first" approach is often prioritized, which focuses on maximizing the performance of the building envelope through insulation and airtightness before upgrading building systems. This methodology reduces the overall heating and cooling demand, allowing for smaller, more efficient HVAC systems. - Publications like *Dezeen* and *Architectural Record* are highlighting a growing trend in "modest" architecture, which favors the creative reuse of existing buildings and the use of biomaterials over new construction to reduce embodied carbon. This aligns with the principles of deep retrofit, which can reduce a building's greenhouse gas emissions by 50% or more. - The UK's Publicly Available Specification (PAS) 2035 provides a comprehensive framework for the energy retrofit of domestic dwellings, emphasizing a "whole-house" approach. This standard ensures that all aspects of the building, including its context, condition, and occupancy, are considered to create a tailored and effective retrofit plan.
