Contact: Ryan Lewis on Slack

Posted: Sep 2020

Anyone interested in helping me to build a web app which gives good accurate calculations of the Manual J for residential homes. This would be a good stepping off point for a real tech startup in the climate space.

What is this:

The Manual J addresses the question: How much energy per hour do I need to add or remove from the building in order to keep it at a comfortable indoor air temperature.

How does this work:

There is a simple linear relationship between a desired Temperature Delta, delta-T and the energy needed to achieve that delta-t in a given hour.Energy needed = **u * area * (Desired delta-T)**The constant u in this equation is called the buildings u -value, and u = 1/R where R is the buildings R-value . You may be familar with R-value if you have ever purchased insulation for a building.

Why do we care:

• If we want to electrify the heating/cooling system of a house we need to make sure the convectors or air conditioners are the appropriate size. Too big and they are wasteful, too small and they are not doing there job.
• These are critical for making choices around how to replace older systems with modern carbon friendly solutions

What is involved:

The goal of the calculation is essentially to work out the buildings R (equiv u)-value

• You need to have a bunch of data on the house, such as its location for deciding on the delta-T
• Floorplans, wall thicknesses, insulation thickness etc.

You can put all this together in a relatively straightforward way to get the buildings block load (e.g. load of the entire building), as well as room-by-room loads.**Existing Solutions:**These are the solutions "approved" by ACCA the society that approves these sorts of things. WrightSoft is more or less an industry standard. It's basically 1990's era tech bootstrapped into modern day. Its really expensive.https://www.acca.org/standards/approved-software