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FAQ: Ensuring Compliance with 2018 Washington State Mechanical Code

Updated: Feb 6

Enhance Your Projects with Seamless ERV Integration

By Gabrielle Glass, Tiscareno architects   

The 2018 Washington State Mechanical Code is now being implemented, requiring the installation of Energy Recovery Ventilation systems (ERVs) in all new multifamily projects. Getting it right from the start is crucial.  

With careful planning, it is possible to avoid conflicts and keep your construction schedule on track. Learn how upfront coordination can impact mid-rise construction.  

What impact will the recent Washington state energy code updates have on my project?  

In the construction industry, code regulations are in a constant state of evolution, and energy efficiency is taking center stage. Washington State has taken a significant step forward by mandating the inclusion of Energy Recovery Ventilators in mid-rise construction. The inclusion of ERVs on projects is adding increasing complexity to mid-rise construction. This results in more time being spent coordinating designs across disciplines and a new set of decisions for the developer to make.  

A well-coordinated set of documents plays an even more critical role with the inclusion of ERVs in a project. These new energy regulations are pushing engineers and architects to adopt coordination and pre-planning techniques that were traditionally reserved for high-rise construction and more complex building types. The implications of this shift are far-reaching, impacting not only compliance but also cost control, project timelines and residents’ experience.

What are ERVs?

Trickle Venting versus Energy Recovery Venting

Energy Recovery Ventilators (ERVs) are systems designed to optimize indoor air quality and energy efficiency by exchanging stale indoor air with fresh outdoor air while recovering and transferring heat or cooling in the process. This dual function not only ensures healthier and more comfortable indoor environments but also reduces the energy load on heating and cooling systems. ERVs are replacing trickle vents in order to supply buildings with fresh air and are an integral component of mid-rise construction in Washington State in order to move the state towards achieving its long-term energy goals. The fresh air entering a space through trickle vents was unconditioned and the heating or cooling system would need to work to warm or cool that air after it had entered the inside space. ERVs pre-warm or cool fresh air that enters a room, reducing the need for mechanical heating or cooling.  

What impact will the inclusion of ERVs have on design process?  Are there new design considerations that need to be taken into account?

ERVs need to be located inside every unit in the building and due to this requirement, some design decisions need to be made early in the schematic design process.  The ERV will need to exit the building either through the building façade or up through the roof. Each choice has benefits and drawbacks including costs, coordination time, aesthetics and occupant experience. ERV routing that exits the building through the façade will require coordination with the design of the building façade and ERVs exiting through the roof will require a location in the unit design. 

The type of system chosen will affect a variety of aspects of the building design including structural design, amount and location of soffits, facade impacts and the square footage of units.  Even the occupant's experience when it comes to accessing the ERV, for filter changes, needs to be taken into account.  All these factors should be considered and weighed when determining the approach taken to meeting the code requirements. 

Coordination between the disciplines should be directed towards mitigating impacts by addressing potential conflicts early in the design process. Coordination ensures that ERV installation doesn't interfere with other critical construction activities, reducing the risk of delays and cost overruns. Ultimately, an up-front collaborative effort results in a smoother construction process, on-time project delivery, and cost savings, while also maximizing the benefits of energy-efficient ERV systems in the building. 

Tradeoffs of ERV system design

Will the inclusion of ERVs impact the project timeline? 

The inclusion of ERVs in building projects introduces a new level of pre-construction coordination between multiple disciplines including Structural Engineers, Mechanical, Electrical, and Plumbing consultants. Planning for upfront coordination time between the disciplines can be a benefit to the overall project timeline by minimizing schedule and cost disruptions later. Adding time for reviewing overlays of each consultant’s proposed solutions reveals discrepancies and clashes early in the design process that might have otherwise gone unnoticed until construction, reducing future scheduling issues during construction.

Coordination of ERV impacts project timeline

What is the most efficient way to meet the new code requirement? Is one approach to meeting the ERV requirement inherently riskier? 

Just like every project, every ERV system has its own constraints and possibilities.  Design considerations for an individual project should be weighed and discussed early in the design process to ensure that the chosen system will support a successful project. Early design meetings that include the client, architect, structural engineer and mechanical engineer should be focused on discussing the overarching goals of the project and which type of ERV system can meet those design goals.  This early decision, involving all stakeholders, can lay out the most efficient approach for the project to avoid potential hurdles down the road. 

Weighing project goals with ERV design


Gabrielle Glass,

Gabrielle brings her extensive experience as a project architect to every facet of development. From initial concepts to the meticulous creation of construction documents, she excels at solving complex challenges and is a sought-after collaborator. With a unique blend of theoretical insight and practical acumen, Gabrielle is adept at balancing design aspirations with code requirements, budget constraints, and construction needs. 


A graduate of the University of Washington College of Architecture, Gabrielle’s recent projects include Solera—a 600-unit, mixed-income development in Renton—where her role in construction administration is pivotal, coordinating closely with contractors, reviewing materials, and conducting onsite assessments to ensure the project delivers on time and on budget. 

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