Getting the heating and cooling systems in a house right isn’t easy. In most cases, the HVAC contractor is in charge of all aspects of design – load calculations (or the lack therof), type and location of equipment, and the layout of ductwork. This raises a conflict-of-interest problem: what’s to stop an HVAC designer from choosing a more expensive system that is oversized with bells and whistles you don’t need? Unfortunately in many houses, HVAC systems severely underperform – they are often oversized, overly expensive, inefficient, and prone to comfort and noise problems. Often this stems from a lack of though put into good design work. Nothing against the HVAC contractors of the world, but their business model generally relies on equipment sales and installations rather than providing detailed design work. If you are building a new house, renovating a house, or changing system types, here are 5 reasons why you might consider having a third party design your HVAC (heating, ventilation, and air conditioning) system:

  1. Expertise: A third-party HVAC design company will have specialized knowledge and experience in designing HVAC systems. They will be able to assess your specific needs, take into account any unique challenges posed by your building or location, and design a system that meets all of your requirements. ACCA Manual J is the most widely recognized method to determine the heating and cooling loads, or the amount of heat that needs to be added or removed from a building to maintain a comfortable indoor temperature. Consider looking for a company that has an ACCA trained designer and that uses ACCA approved software.
      ACCA Certified Residential System Design

2. Efficiency: An HVAC system that is properly designed and installed will operate more efficiently, which can save you money on your energy bills over time. A third-party design company can ensure that your system is optimized for maximum efficiency. Efficiency starts with detailed load calculations and right sized equipment for your particular home. An oversized heating or cooling system will consume more energy than is necessary to heat or cool the space, leading to higher energy bills. Doing a detailed Manual J calculation takes into account many variables, including:

  • The size and orientation of the building
  • The building’s construction materials, such as the walls, roof, and floor
  • The type and quality of insulation used in the building
  • The number, size, location and performance of windows and doors
  • The number of occupants and their activities
  • The type and efficiency of the heating and cooling equipment

After the building’s loads are determined the designer will select the equipment to provide the right amount of heating and cooling. Our approach is to look for highly efficient equipment to provide heating and cooling. In most cases these days, that means a heat pump system of some type. A 3rd party designer should have knowledge of all the major types and brands of heat pump systems and help select the best fit for your home.

Ductless Heat Pump

3. Comfort: A high performance heating and cooling system is more than a piece of equipment with a high efficiency rating. It’s one that keeps people warm in winter, cool in summer without them ever noticing it. That means they don’t hear it, they don’t feel air blowing on them from the vents, and no matter where they are in the house they are, they’re comfortable. While air temperature is one aspect of thermal comfort most people are most familiar with, other factors like radiant temperature, air speed, and humidity also play a major role. Comfort in a home also requires a good building enclosure to separate us from the outdoors. No matter how powerful the HVAC system, you’re not going to be very comfortable in an open-walled tent when it’s 15° outside. A third party HVAC designer should have expertise with the building enclosure and may even be able to make suggestions that can help reduce heating and cooling loads.

Thermal Imaging

4. Compliance: HVAC systems are subject to a variety of codes and regulations, and a third-party design company will be up-to-date on all of the relevant standards. They can help ensure that your system meets all legal requirements to fast-track the permitting process. The codes that come up the most often in residences are the Washington State Energy Code and Washington Residential Code. These codes specify things like minimum equipment efficiencies, ventilation system types and minimum airflows, duct location and leakage. These codes change every 3 years and it’s important the system designer be aware of all the various code provisions that apply. You may also want an HVAC system to meet specifications for green building programs like Energy Star, DOE Zero Energy Ready Homes, or PHIUS. We can help design a system that meets the heightened requirements for these programs.

Green Building Programs

A few of the different codes and programs we can design systems to meet.

5. Cost Saving: There are several ways having a third party designer can save costs:

  • Right-sizing equipment: Oversized HVAC equipment can be more expensive to purchase and operate than equipment that is properly sized for the building. A third-party HVAC designer can perform a load calculation to determine the building’s heating and cooling needs and recommend appropriately sized equipment.
  • Equipment selection: A third-party HVAC designer can recommend high-efficiency equipment that can significantly reduce energy consumption and operating costs over the life of the equipment. Unlike many contractors who are dealers for particular brands, we are brand neutral and can consider what’s best for our client’s needs.
  • Energy modeling: A third-party HVAC designer can use energy modeling software to simulate the performance of different HVAC system options and identify the most cost-effective solution.
  • Building envelope analysis: Improving the building envelope through insulation and air sealing can reduce the heating and cooling loads on an HVAC system, potentially allowing for smaller, less expensive equipment. A third-party HVAC designer can analyze the building envelope and recommend improvements that can reduce HVAC costs.


Overall, having a third party design your HVAC system can provide you with peace of mind, improve the efficiency and functionality of your system, and potentially save you money in the long run.