https://communities.bentley.com/products/building/performance/f/hevacomp-forum/110646/part-l-simulation-not-recognising-changes-made-within-part-l-design-databaseHi have just been modelling a building - Level 5 EPC and I have been adjusting the air permeability and lighting information within Part L design database. Once I had the building &#39;passing&#39; within Part L Simulation - I then went back into Part L designen-USTelligent Community 12https://communities.bentley.com/thread/337353?ContentTypeID=1Mon, 07 Sep 2015 09:20:04 GMT6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:a1bc32d8-1b0e-427c-bc35-7bdd79401ac5Duncan Brown<p>Kevin</p> <p>There are a couple of things that come to mind in the first instance:</p> <p>When you are changing data in Part L, do you have the individual/default data option set correctly? If - for example - you have set up your rooms with individual data and are changing the default data option, then these changes won&#39;t carry forward. (<a href="/products/building/performance/w/building_performance__wiki/5640.defining-air-permeability">See here </a>for more information)</p> <p>Also; are you existing the Part L program before going into the Simulator program? You need to exit Part L to ensure that the data is written back correctly.</p><div style="clear:both;"></div>