HVAC, Ventilation & Dehumidification Design

Overview

The most common HVAC failure pattern in multifamily construction is not mechanical breakdown — it is design error. A system oversized for the space short-cycles, removing heat but not moisture. A duct system never designed to the actual load delivers too much air to some spaces and too little to others. A ventilation strategy that worked in a loosely built 1980s structure creates chronic negative pressure and mold risk in a tightly sealed modern building. Equipment replacement without a load calculation, duct design, and ventilation analysis does not solve these problems. It replaces them with a newer version of the same problem.

When to Use This Engagement

This engagement is appropriate when: an asset manager is replacing end-of-life HVAC equipment and needs an independent design basis before accepting contractor proposals; a developer is specifying mechanical systems for new construction and requires Manual J, Manual S, and Manual D documentation; a building in a high-humidity climate zone has chronic humidity complaints that equipment replacement has not resolved; or a ventilation system is generating IAQ complaints, pressure imbalances, or condensation issues that require a design-level solution.

What We Investigate and Design

Design services include Manual J load calculations establishing heating and cooling loads by zone; Manual S equipment selection matching system capacity to actual load; Manual D duct design covering sizing, layout, and air distribution; ventilation design to ASHRAE 62.1 and 62.2 standards including ERV and HRV specification; dedicated dehumidification design for high-humidity climate zones; filtration specification including MERV ratings and static pressure impact analysis; and make-up air and pressurisation strategy for multifamily corridor and unit applications.

What You Receive

A complete mechanical design package including: load calculation report; equipment selection specifications; duct design drawings and documentation; ventilation and dehumidification design documentation; and a commissioning protocol for verifying installed system performance. All documentation is suitable for contractor bidding, permit submission, and commissioning verification.

Why Independence Matters

A mechanical design produced by the contractor who will also install the equipment is not a neutral document. Equipment selection by the seller of that equipment is not independent engineering. Building Science Advisors designs mechanical systems without selling or installing any equipment. The design is optimised for the building’s actual load — not for the contractor’s preferred product line or installation efficiency.

The Decision This Protects

Equipment procurement and installation approval. A specification-grade independent mechanical design gives the owner a documented standard against which contractor proposals can be evaluated, bids compared, and installation verified. Without it, the owner is entirely dependent on the contractor’s self-interested recommendation.

Request an Assessment

Contact Building Science Advisors to discuss mechanical design services for your asset or development.