The architectural portion of the plans for the new Passive House in Derwood, MD has been approved by the Montgomery County building authorities.   Site plan review is on going.

Concurrently, PHIUS‘s review of the project is nearly complete.   Ryan Abendroth and Lisa White have scrutinized nearly two dozen, densly detailed Excel worksheets that comprise the Passive House Planning Package (PHPP), and have identified several items that needed refinement.   Final revisions should be complete later today.

The long and short of the process is, our initial design was extremely close to meeting the Passive House Standards .  To make the nut, we will have to improve the thermal performance of the building envelope–so for simplicity and economy, we have chosen to add 1/2″ of insulation under the floor slab.