Manual-J Load Calculations
Air conditioning systems make up the greatest portion of a home’s energy costs; they also greatly impact the comfort and well-being of the home’s occupants. A Manual J is the first step towards having a HVAC system that effectively and economically conditions a home's environment. Austin Auditors' knowledge and experience can help ensure that you get a quality Manual J and your home gets the correct amount of cooling and heating.
The best practice to calculate the heating and cooling load of a home is by completing a Manual-J load calculation.
What We Need to Complete Your Manual-J
In calculating the Manual-J, we assess the building to determine how much air each room will require to provide comfort. The calculations factor in all surfaces of the building envelope, with their areas and insulation levels. We give each wall its proper orientation and input the walls’ building materials, i.e. windows, doors, insulation level, etc. The results of the Manual-J specify the per room BTUH of heat gain in the summer and heat loss in the winter.
We will need the below information to best complete your Manual-J. You can submit it in our contact form when you place your order or you can email it to us at email@example.com if ordering by phone.
If you do not have all of the below information, please submit what you have and we can fill the gaps as we move forward.
- Plans - We prefer PDFs. They will need to be drawn to scale. Simple paper drawings are acceptable, as long as they are to scale or have dimensions noted.
- Envelope - What materials are your floor, walls, and ceiling/roof made of?
- Insulation - the attic/roof, walls, and floor insulation levels of the house.
- Windows - the U-value and SHGC of the windows.
- Doors - Describe the solid doors to us (example: solid wood, insulated steel).
- Internal loads - If you know of specific internal loads that are out of the ordinary, let us know what they are and the room in which they will be.
- Orientation - What direction does the front door face?
- Infiltration - What is the estimated air-change rate of your project? You can give this to us in ACH50, a target blower door result, or qualitatively (super-tight, kinda-tight, etc.). The more specific you are, the more accurate the result.
- Ventilation - Do you have an active ventilation system? If so, please describe it to us.
- Duct location - Give a description of the area in which you plan on installing the ductwork for each system (attic, crawl space, between floors, etc.).
- Duct leakage - How tight will the ducts be? Will they be pressure tested after installation?
Ordering your Manual-J
To order your Manual-J calculations, simply fill out the contact form at the bottom of this page with the information in the bulleted list above. You can also email us at firstname.lastname@example.org.
Be sure to include the street address of the home, as well as your contact information, just in case we need to contact you for additional details. We will email you back to confirm receipt of your order and let you know when you can expect to have your resulting calculations back.
For any questions regarding Manual-J calculations, please call us at 512-879-3567.