RI03: Nearly-zero energy buildings – retrofitting to meet the standard

This document presents a method for applying the nearly-zero energy building (nZEB) standard to existing UK commercial and residential buildings. The findings presented are based on analysis supported by dynamic simulation modelling of UK buildings, aiming to demonstrate the potential benefits but also highlight the risks associated with achieving such high energy-efficiency standards within the built environment. This work builds on that presented in TM55: Design for future climate — case studies (CIBSE, 2014).

Four case studies are utilised to explore what it means to achieve the nZEB standard and apply it to existing UK buildings. These have been presented individually within this publication to focus on the various outcomes of each building type. The highlighted outcomes demonstrate that with well thought-out design decisions and careful consideration of a building’s resilience to a changing climate, the standard can be achieved — and this can introduce long-term cost and energy benefits. There is a large amount of work that needs to be done, and many questions to be answered, before fully transitioning to nZEBs. 

Topics covered include:

• What is the nZEB concept?
• Key issues faced by the industry
• Key findings
• Case study 1: Typical pre-1990s detached dwelling – Bracknell
• Case study 2: Overheating in a retirement village — Hughenden Gardens
• Case study 3: Historic hotel — The Hilton Edinburgh Grosvenor
• Case study 4: Typical UK purpose-built hotel — The Hilton Watford
• How does this affect building services engineers?
• Wider implications
• Challenges and limitations
• Moving forward