Home heating, ventilation, and air-conditioning focuses health, comfort, and energy. Homeowners should know what’s being installed in their home, what it does, and be able to make decisions that provide the largest benefit.

Do you really need an HVAC consultant? The answer might be NO, contractors can use “rules of thumb”, usually pull the necessary permits, and install the equipment. However, theACCArecommends that you insist on design in accordance with the Manual J residential load calculation procedure. Manual J is the official standard for residential load calculation and is required by many building codes around the country.  The size of your system matters – don’t just size the equipment based on the existing equipment, especially if you’ve replaced windows, added a ventilation system, air sealed your home, or upgraded insulation.




Finding a contractor capable of proper design or enlisting the services of an engineer is critical to achieving optimum performance, proper sizing, and clean installation as well as educates you about the options available. Registered design professionals, typically Professional Engineers, are required to sign off onEnergyStar Certified Homes if you intend to achieve certification. Sisu Engineering has LEED Accredited Professionals who are experts in building energy optimization, comfort, and sustainable design measures. So whether you’re building your new dream home, adding to your existing home, or making improvements to your home we can provide a design that meets your needs and your budget.


Stage 1 – Concept & Evaluation

The first stage is Concept – and this is where most decisions are made. We explore the system options available, your priorities (initial cost, energy, indoor environment, etc.), and any incentives available for you.


Review MassSave Energy Audit (if available)

 Determine Systems 

Discuss Your Priorities

Perform Payback Calculations



Tax Credits

Utility Rebates

Stage 2 – Design Development

Much of our experience is consulting architects on the design of mechanical systems. We understand that working on your project is a team effort and we are here to be part of that team.  



Manual J, S, D Calculations

Review by Professional HVAC Engineer

Product Evaluations

Work with Architect, Homeowner, and/or Contractor


 Coordinate with Floor Plans 

Optimize Mechanical Spaces

Stage 3 – Construction

We love watching our designs come to life. Every job and every site is different and posses unique challenges. We will respond to your contractors questions and verify that systems are being installed in accordance with the design. 


Provide Sealed Permit Documents

Meet with Building Inspector, if required

Support the Contractor



Monitor Installation Throughout Construction

Phased Inspection

Concealed Components

Stage 4 – Verification & Commissioning

Making sure your system is performing the it should be is critical. Things get missed during construction and may not turn up for a season or two – well after you contractor is gone. We come in to verify system were installed in accordance with the documents and test them with the contractor.  


Test Your System at Varying Conditions

Confirm Final Installation

System Configuration

Control System Function Checks


Provide Final Affidavits, if required

Follow-up Comfort Survey

Closeout Documentation

We take pride in accurate, timely, and efficient residential designs. All designs are performed under the supervision of a Professional Engineer – we stand behind our engineering and designs. We work closely with our clients on every project with a professional approach. Renovations and additions may require a site visit because evaluating existing conditions is a priority. We provide HVAC designs to architects, builders, homeowners, developers, and real estate professionals. These services apply to the following types of buildings:

  • Custom Built Homes
  • Luxury Custom Homes
  • Modular Homes
  • Sub-Division Production Homes
  • Renovations and Additions
  • Residential Complexes and Developments


Our home designs leverage Wrightsoft Universal for performing initial calculations and the designs are reviewed by a Professional Engineer and can be sealed upon request. A typical airside HVAC design will include the following:

Room by room heating, cooling, and outside air requirements. Each exposure (north, south, east, and west) and room type will have different requirements.

  • Your cooling equipment sized properly to control humidity, not short cycle, save energy, and most importantly cool your home comfortably.
  • Your heating equipment sized properly to save energy and heat your home comfortably. Heating energy is one of the largest utility expenses in your home so it must be done correctly.
  • A rough estimate or price – all businesses need to make money; however, if your contractors price is much lower than this estimate, the quality will be low, if it’s significantly higher, you’re being over charged and should continue searching.
  • Recommended controls scheme for you contractor to follow. All new HVAC installations should leverage proven technology to reduce energy consumption with little to no added expense.

Systems that are not air based – like radiant floors or energy recovery – will receive similar documentation customized to the systems selected.

Local building departments are starting to request professional documentation in order for a contractor to get a permit – this trend will continue to grow and for good reason. At a minimum Manual J calculations, a Manual D duct design, and a gas flow diagram are requested.



Full design services

When building or renovating complex homes, luxury homes, or a unique system we recommend full engineering and design consultation services – we produce detailed design schematics, engineering calculations, drawings and equipment lists; as well as, attend meetings, phone calls, and complete product reviews. Our design consultation will also include an allowance for working with code officials, on-site meetings, and quality assurance inspections. Please request a quote for a residential or commercial design proposal and we can discuss your home, plans, and requirements. All of our calculations are completed using software compliant with ACCA or ASHRAE, reviewed, and approved by a Professional Engineer. A P.E. seal will be affixed to all design documents produced under our full design and consultation services.


Limited design services

For single tasks and less complex homes clients may chose to use our limited services shown in the table below – we provide calculations, duct sizing, equipment certifications, and energy compliance paperwork. Limited HVAC design services include a review by a professional engineer visit our store for pricing and packages. Custom multi-project packages are available for contractors, developers, and architects – just shoot us an email or request a quote!


Proper load calculation not only ensures your homes ability to control temperature, it saves you money. A properly designed and functioning system saves energy. ACCA Manual J is a method used to determine actual thermal loads for residential structures.


Duct design can make or break a project. Manual D was developed by ACCA and it ensures a proper duct design. Our engineers will also review the design against ASHRAE and SMACNA duct standards.


ACCA Manual S is used in conjunction is ACCA Manual J by certifying that the equipment will deliver the amount of cooling/heating required by the ACCA Manual J Calculation.


RESCHECK, or similar, is required by many municipalities and have three objectives:

1. Verify the documentation

2. Verify equipment efficiency meets code

3. Verify all information needed to conduct a field inspection is included on the plans.


Properly sized ductwork and equipment is critical to reducing radiated noise. We can recommend systems, equipment locations, and acoustical batting to reduce noise further


Your homes systems will be sized to heat, cool, and ventilate your home to optimal temperatures improving the indoor environment.


We provide high efficiency designs by sizing systems properly and through advanced control strategies. Most projects include energy star appliances as the basis of our design