Washington State DOAS Requirement for Commercial Buildings Takes Effect July 1, 2017

 In Blog, Energy Efficiency Policy

Summary of DOAS Requirement:

Washington State, when adopting the 2015 International Energy Conservation Code, passed new commercial construction code that requires a Dedicated Outdoor Air System (DOAS) with energy recovery for office, education, and retail buildings; and for libraries and fire stations (WAC 51-11C-40360, Sections C403.5 and C403.6). Commercial spaces have been required to supply outdoor air at certain volumes for decades. What is new is separating ventilation air from the “HVAC” system–from typical heat/cool equipment’s high-wattage, high-volume fan blowers needed to achieve comfortable indoor temperatures, during peak outdoor weather conditions. Now, the heating and cooling system must be able to be turned off, while the ventilation continues, whenever those indoor temperatures are fine. The intent of the new code is to save 30% to 60% of HVAC energy, in Ecotope’s analysis of three “base case” buildings provided to the State of Washington.[1]  To reach those savings, the DOAS must also include energy recovery technology and bypass economizer operation.

Ventacity is ready to assist new construction and retrofit projects meet this new code easily, with ultra-efficient heat/energy recovery equipment.
Call us: 503-208-7331

Code Language Highlights:

C403.5 – DOAS required: “Outdoor air shall be provided to each occupied space by a dedicated outdoor air system (DOAS) which delivers 100 percent outdoor air without requiring operation of the heating and cooling system fans for ventilation air delivery.”

(Exceptions: (1) Occupied spaces that are not ventilated by a mechanical ventilation system and are only ventilated by a natural ventilation system per Section 402 of the International Mechanical Code. (2) High-efficiency variable air volume (VAV) systems complying with Section C403.7, which has 16 energy-conserving criteria to be met for exception to be allowed.)

C403.6.1- Energy recovery ventilation requirement: “The DOAS shall include energy recovery ventilation that complies with the minimum energy recovery efficiency and energy recovery bypass requirements, where applicable, of Section C403.5.1.”

(Exceptions: (1) High-occupancy areas (>25 people per 1000 sq ft) if Demand Control outdoor air can be reduced >50%. (2) Systems installed for the sole purpose of providing makeup air for exhaust systems of pollutants such as fumes, dust, kitchen grease, smoke, and biohazards.)

C403.5.1 – Minimum energy recovery efficiency: “The energy recovery system shall have the capability to provide a change in the enthalpy of the outdoor air supply of not less than 50 percent of the difference between the outdoor air and return air enthalpies, at design conditions. Where an air economizer is required, the energy recovery system shall include a bypass or controls which permit operation of the economizer as required by Section C403.3.” (Specific design airflow rates are required, according to percent outdoor air supplied, climate zone, and annual hours operating.)

(Exceptions: Nine exceptions, primarily for pollutant exhaust systems; high-efficiency VAV systems; dehumidifying needs; or for occasional cooling in cold climate zones.)

NEEC Provides Energy Code Guidance and Training:

Northwest Energy Efficiency Council is the source of energy code technical assistance and regular trainings for ‘non-residential’ building owners, including multi-family owners; commercial HVAC system designers, including architects, engineers, and energy consultants; and general and mechanical contractors. NEEC is a non-profit trade association for “the energy efficiency industry” with a mission to influence energy policy in Oregon, Idaho, and Montana as well as Washington.

  • NEEC holds trainings around Washington in 2017 and will publish a substantial “DOAS Design Guide” in Summer 2017, authored by a team of experts from Ecotope and NEEC.  Ventacity eagerly supports high-performance ventilation education. We hope to share NEEC’s design guidance widely.
  • NEEC’s energy code seminars happened in Kennewick, WA on May 23, Vancouver May 24, and the next is in Renton on June 8, Burlington June 20, East Wenatchee June 22, and in Olympia, Bremerton, Olympic Peninsula, Yakima and Spokane later this summer and fall.
  • NEEC Energy Codes website includes technial assistance such as Compliance Forms: “NEEC provides technical assistance, compliance forms, and educational resources for the Commercial Provisions of the WSEC. Commercial Provisions apply to all commercial occupancies, [to] Group R-2 and R-3 occupancies greater than 3 stories above grade, and [to] Group R-1 of all building heights. Many building jurisdictions require that Compliance Forms accompany project permit submittals … Educational resources include classroom trainings, webinars, fact sheets and other informational tools.”

NEEC’s technical support team responds to questions and technical resource inquiries:

  • Email WSEC@neec.net
  • Telephone the technical support team manager – Lisa Rosenow, 206-624-0283

[1] Heller, Jonathan, and NEEA. “2015 Washington State Energy Code Development Standard Energy Code Proposal Form” (2015, March 10). State of Washington State Building Code Council submission, pages 3-4, 6. (Available online @ https://ventacity.box.com/s/jmfnrrog7a5c0gaq41773htq65bdo7a8 )

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