Pursuing the future of energy efficient homes since 2015
DYI Manual J Energy Modeling
Learn to create your own Manual J Models w/ our course on Heatspring
Manual J calculations are required by more organizations and programs every day, including:
- Certifications, like Passive House, HERS, DOE
- Electric Utilities, to qualify for rebate programs
- Building designers, for decision-making in the design phase
Already an essential design tool, energy models are used for code compliance, utility incentives & green building certifications. As we move towards a resilient, sustainable & emission free future, energy modeling should be used as a tool for decision making. Not only for sizing equipment but also for shaping buildings & selecting materials as well.
New Homes
Existing Homes
New does not equal energy efficient
With the increasingly tight construction methods, materials and requirements of new homes, energy modeling has become increasingly important.
Used to accurately size, select and locate HVAC equipment in new homes, energy modeling is becoming more and more essential.
Energy modeling can be a helpful tool in the design phase as well as prior to, and into construction.
Existing Homes
Existing Homes
Replacing the boiler or adding AC to your existing home?
Energy models for existing homes can be a useful tool when it comes to replacing outdated HVAC equipment.
Chances are the HVAC equipment in your home was sized using a ball park guesstimate. Likely leaving you with oversized equipment or even undersized distribution. Improperly sized HVAC equipment often leads to short cycling, increased wear and tare, increased operating costs and reduced operating life for your equipment.
Outdated Methods
Outdated Methods
Energy modeling has been a part of commercial construction for decades. However, it is fairly new in residential construction. Historically residential builders and HVAC installers have been using a rule of thumb - a BTU/SF guesstimate.
The BTU/SF method does not works well with today's tight buildings & materials. More and more obvious becomes the over sizing of HVAC equipment that this method leads to.
A Quick Case Study
Two of our stock plans for example: The same designed envelope, R-values, window selections, assemblies & location
- A 1200 SF home = 8 BTU/SF
- A 750 SF home = 16 BTU/SF
That difference is double!
Plus, the variation is even greater when modeled room by room.
We found for our own plans that one room may need 25 BTU/SF and another may need just 4 BTU/SF, on the coldest day of the year.
Manual J Energy Models are used to size the peak heating & cooling loads of a building. Those loads are significantly based on the exterior surface area & materials of a building, not it's volume or square footage.