HVAC System Air Leakage Requirements for Deep Energy Retrofit Projects

摘要

One of the major outcomes of the recently completed International Energy Agency (IEA) Energy and Buildings and Communities (EBC) Annex 61 "Business and Technical Concepts for Deep Energy Retrofit in Public Buildings " is a Technical Guide (EBC 2017a) that contains a list of core energy efficiency technologies generated from the results of case studies (EBC 2017b), from surveys and discussions conducted at the ASHRAE Technical Committee (TC) 7.6, "Federal Buildings " working group meetings in 2013 and 2014, and from previous experience and research conducted by the EBC Annex 61 team members. These technologies, when applied together (as a bundle), will reduce total building site energy use by about 50% (including plug loads). Technical characteristics of these building retrofit technologies, grouped into a core technologies bundle, have been studied through modeling and life cycle cost (LCC) analysis for representative national climate conditions. Among these technologies are those related to the building envelope; lighting; and heating, ventilating, and air-conditioning (HVAC) systems. When a building undergoes a deep energy retrofit (DER) that is conducted as part of a major renovation project, the duct system is usually replaced. Replacing it with a well-insulated and airtight system is one of the most cost-effective energy efficiency measures available. One reason is that the airflows through air-handling units (AHUs) connected to ducts must be sufficient to compensate for air leakage involving ducts and duct-mounted components (HVAC system air leakage). These AHU airflows account for a large fraction of the energy use in buildings. For example, in the United States, HVAC system air leakage is ranked as the primary source of energy inefficiency in commercial buildings; it wasted an estimated $2.9 billion in 2005 (Mills 2009). Based on research results and experience from the United States and around the world (especially in Scandinavia), this paper provides recommendations on cost-effective targets for ductwork airtightness and a quality assurance process for achieving these targets.