A simulation is not a building. Before I was licensed, I did a fair number of small residential additions in Florida. For a building permit, a Manual-J calculation in accordance with the Florida Energy Code was required.
At that time, do to market conditions, 1.5 ton (18k BTU) heat-pumps were about 1/3 less than 1 ton (12k BTU) units. However, oversizing the unit to the cheaper size would cause the calculation to fail and permit to be denied.
These were small projects and the difference in up front costs could be relatively substantial and the likelihood of long term payback minimal because the zoning assumptions upon which the calculations were based did not exist in the real world.
So, instead of the default of one occupant for the addition, I would enter two, or three to get the result that was needed.
I was not implying that there was a problem with the software at all. Nor with the market. Or even with the permitting process.
A competent designer gets the results they want within whatever constraints are created by the system.
I made a design decision to use three occupants based on the design decision to use a 1.5 ton (18k BTU) HVAC system based on a cost benefit analysis based on the Owner's goals. A permit for construction being among the Owner's goals.
LEED has basically been working the same way. The Owner specifies a Gold Rating. The designer designs the documentation for a Gold Rating. They design the building based on other criteria in addition to the Gold Rating.
To be clear, it was not as if my goal was to subvert the system. I could have specified a 1 ton (12k BTU) unit. Inevitably, I would receive a call from my client because the AC subcontractor bid a 1.5 ton unit and that was what was on site and at least partially installed and had been red tagged by the inspector just because it was his job to red tag it.
Then we would all spend a lot of time back and forth and the end result would be that the inspector would be a little pissed off because the 1.5 ton unit got approved by his boss based upon common sense over the fact that it didn't really matter and that energy calcs for a small addition are meaningless and the energy code was really designed for larger projects and all we were really doing was shuffling paper.
And shuffling paper is largely what LEED is all about - at least up until now.
At that time, do to market conditions, 1.5 ton (18k BTU) heat-pumps were about 1/3 less than 1 ton (12k BTU) units. However, oversizing the unit to the cheaper size would cause the calculation to fail and permit to be denied.
These were small projects and the difference in up front costs could be relatively substantial and the likelihood of long term payback minimal because the zoning assumptions upon which the calculations were based did not exist in the real world.
So, instead of the default of one occupant for the addition, I would enter two, or three to get the result that was needed.