The goal of EAp2 is to establish the minimum level of energy efficiency for the proposed building and systems to reduce environmental and economic impacts associated with excessive energy use. Introduction The project is a Core and Shell building in Germany with leasable space for office and retail tenants. The Whole Building Simulation has been prepared in accordance with ANSI/ASHRAE/IESNA Standard 90.1-2007 (ASHRAE 90.1). For larger retail stores, vestibules and revolving doors are unusual entrances for contemporary retail buildings in Germany and would place a disadvantage on the marketability of the tenant spaces. In lieu of vestibules, air curtains are planned for the high traffic entrances to the retail areas to prevent infiltration and improve energy performance. Project Approach The design team would like to propose an alternative compliance path for the Mandatory Provision of ASHRAE 90.1 Section 5.4.3.4 that requires vestibules or revolving doors for entrance spaces greater than 3000 sq ft. This will apply mainly to tenant retail areas. For all entrances requiring vestibules as per ASHRAE 90.1, it is planned to utilize air curtains. Note that the local Codes do not mandate vestibules and they are uncommon for German retail stores. The latest version of the International Green Construction Code, IgCC 2012, approves the use of air curtains as a substitute for the vestibules required by the current International Energy Conservation Code (IECC). Per Section 605.1.2.3 of IgCC, Where a building entrance is required to be protected with a vestibule in accordance with the IECC, an air curtain tested in accordance with ANSI/AMCA 220 is permitted to be used as an alternative to separate conditioned space from the exterior. Air curtains were approved as a substitute for vestibules in the IgCC because they were determined to prevent infiltration and heat loss equally or more effectively than vestibules. The study Air Curtains: A Proven Alternative to Vestibule Design by Berner International utilized computational fluid dynamics (CFD) modeling to demonstrate that air curtains used with automatic doors at building entrances are 10% more energy efficient than vestibules. For entrances with high traffic such as the case for retail, air curtains were calculated to reduce space heat loss by as much as 20-40% compared to standard vestibules. The IECC currently does not include air curtains as an alternative to vestibules, but this measure will be considered by code committees next year. Yet, air curtains are already approved as an acceptable alternative by the IgCC, which can be considered the first step in the approval process for the next version of the IECC. In addition, the USGBC refers to the IgCC as a new code baseline for greener building construction that is complementary to LEED, per USGBC Press Release. Air curtains have been used as an acceptable energy conservation measure to achieve EAc1 points. Approving air curtains as an alternative to vestibules at building entrances meets the intent of EAp2 and ASHRAE 90.1-2007 Section 5.4.3.4, with the added benefit of potentially improved energy performance. Additionally, retail buildings pursuing LEED would not be disadvantaged by losing leasable tenant space or reducing green space as a result of an increased building footprint and by adding further restrictions to building owners trying to find retail tenants in a highly competitive market. For the areas listed in ASHRAE 90.1-2007 Section 5.4.3.4 that would require vestibules, the project team will submit the following: 1. Drawings with locations of air curtains at main entrances 2. Air curtain manufacturer and model number The air curtains will also be commissioned as part of EAp1, Fundamental Commissioning, and EAc3, Enhanced Commissioning, if part of developer scope. Please verify that the above approach is acceptable to satisfy the requirements of LEED-NC/CS 2009 EAp2 for a project in Germany.