Tips to design multifamily and mixed-use buildings: Codes and standards

Multifamily dwellings and mixed-use buildings are becoming more prevalent. Learn about codes and standards for engineering systems in these residential buildings.

By Consulting-Specifying Engineer July 26, 2017

  • Brian Berg, PE, LEED AP, CEM, Associate Principal, Glumac, Irvine, Calif.
  • David Crutchfield, PE, Principal, RMF Engineering, Charleston, S.C.
  • Kieran Healy, PE, Mechanical Engineer, CCJM, Chicago
  • Lui Tai, PE, Technical Services Director, JENSEN HUGHES, Toronto
  • Robert J. Voth, Executive Vice President, Bala Consulting Engineers, King of Prussia, Pa.

CSE: Please explain some of the codes, standards, and guidelines you use during the design process. Which codes/standards should engineers be most aware of in their design of engineered systems in such projects?

Healy: When designing projects within Chicago, the Chicago Energy Conservation Code 2015 (CECC, which is a localized version of the International Energy Conservation Code; IECC) often plays a big role when deciding the type of engineered systems to use or which features must be included in a system. When using the CECC or IECC, engineers should generally be well-versed in the exceptions that may apply to their project to avoid specifying unnecessary equipment that may add unneeded cost and operational complexity to a project.

Tai: In Canada, national building codes and fire codes are sometimes adapted by provinces and made into provincial building and fire codes. For life safety system designs, the codes would reference other applicable Canadian and international standards. Typically, fire alarm designs are governed by UL of Canada; standards and sprinkler designs reference NFPA standards.

Berg: As energy codes get more aggressive, ensure that initial and ongoing code-compliance calculations are performed to help inform the architect of envelope limitations and what impact desired envelope designs have on the mechanical and lighting systems. The additional costs of some of the needed, premium MEP systems to achieve a certain envelope design could be enough for the architect to rethink glazing performance or design to remain within budget. This comes up time and again on these large mixed-use projects, and we make sure we’re always keeping an eye on the energy component from the conceptual phase on through design. We’ll maintain constant communication with the architect on where the building stands with regards to energy compliance.

CSE: What are the most challenging codes and standards to follow for such structures? What makes them so challenging?

Tai: Because the codes and standards are prepared by different committees, sometimes in different countries, there can be conflicting requirements. It is sometimes difficult to know which requirement would prevail. Also, the use of terminology and defined terms is different from code to code, which makes the interpretation even more difficult.

Berg: Parking garage exhaust and make-up air requirements are sometimes a challenge because parking is always buried in these mixed-use complexes, and getting air in and out requires some gymnastics and creative coordination with the architect. Restaurant challenges always arise because there is typically parking below and residential above these, so treating the grease exhaust and grease waste is always a bit tricky when complying with codes.

CSE: What are some solutions/best practices to ensure that multifamily dwellings and mixed-use buildings are in compliance with codes and standards?

Berg: Have a code consultant on board early, meet in person with city and fire officials to get important decisions made and understood by all parties, and document everything.

Healy: One solution is to include an integrated MEP coordination sheet at the front of the MEP drawings where all equipment requiring building utilities are scheduled with their specific utility requirements. This table ensures the designers and contractors know what disciplines need, to make sure they are including necessary services to all applicable equipment. This sheet also can highlight the applicable codes that may have an impact on the design of those equipment. Care should be taken to avoid duplication and potential ensuing conflicts between the drawings and specifications if one changes and the other isn’t revised. However, there can also be references to the applicable specification sections for each piece of equipment to ensure the correct codes and standards references are followed without duplication.

Tai: For every jurisdiction, it is important to know the applicable code that applies to the multifamily dwellings and mixed-use buildings. For example, in Ontario, the retrofit requirement for a retirement home would differ from that for a residential rental building. Authorities often overstep their authority by requesting changes that are not retroactively applied to some existing buildings. If in doubt, always consult with a code consultant.

CSE: How are codes, standards, or guidelines for energy efficiency impacting the design of such buildings?

Tai: Energy efficiency is now part of the building code requirement in Ontario. Even though it has not yet made a significant impact to our design, the trend is definitely moving toward achieving it. For example, LED visual strobes will soon replace the traditional high-intensity strobes, which draw a lot of power. This will, in turn, demand smaller power supplies and smaller gauge field wiring, leaving a much smaller ecological footprint.

Berg: Higher-performing envelopes and higher-performing HVAC and lighting systems are being implemented to meet current energy codes. Architects are still designing many predominantly glass buildings because the market really demands it at the moment, but that glazing is high-performing, the accompanying HVAC systems are extremely efficient, and the connected lighting loads and lighting controls are aggressive.

CSE: What new code or standard do you feel will most impact multifamily dwellings and mixed-use buildings? This may be a code that your authority having jurisdiction (AHJ) has not yet adopted, but you feel will directly impact your work.

Berg: Three-story and less multifamily new-construction buildings in California will need to be designed to net zero energy standards starting in 2020. That’s the next code cycle, but many developers are not fully aware of the requirements, so education needs to occur with all parties in the marketplace.

Healy: With recent changes to the LEED v4 rating system, more property owners will begin pursuing LEED ratings for buildings that are 4 stories and higher, leading to different design approaches than what currently occur. The added flexibility in selecting whether to use the Multifamily Midrise or the New Construction rating system will reduce some of the past issues that made multifamily certifications extremely costly for owners and difficult to design for architects and engineers.

Tai: With the increase in hybrid or electrical vehicles on the road, a new code requirement might be added for charging stations inside the garage for multifamily and mixed-use dwelling buildings. There is still a lot of work to be done to standardize the charging requirement between the many automobile manufacturers, however, before the building code can request that charging stations be provided in these multifamily-dwelling buildings.