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New in November 2026

Updates

  • We've added a new Temperature configuration modal which allows you to:
    • Easily switch between 99th and 99.6th percentile outdoor design temperature in a project
    • Customise the mean annual (or ground) temperature and adjoining temperatures of a project;
    • Use temperatures included in the new CIBSE 2026 Domestic Heating Design Guide.
  • The survey task has been extended:
    • The "Heat emitters section" has a new "Heat emitter photos" subsection. Upload photos here to show on the plan and the technical report.
    • A new "Room details" section has been added, which contains room notes and photos. They're also shown on the plan and the technical report.
  • Clicking on a room in the floor plan will now bring up some new tabs:
    • Overview which shows the room details, including annual demand of the room and a list of emitters in the room.
    • Survey where you can upload notes and photos of the room and emitters.
    • Materials where you can view the materials used in each room.
    • Heat loss where you can view a breakdown of fabric and ventilation heat loss calculations for each room.
  • You can now toggle on measurements in the floor plan to view room dimensions.
  • A new "unheated" room type is available to use.

Fixes

  • Fixed an issue where multiple dormers were not adding the same heat loss for each dormer over a room.

  • Fixed dormers causing heat loss for rooms in which they are not a part of.
  • Fixed ground floor u-values using the incorrect value in the CIBSE Domestic Heating Design Guide lookup table for most rooms.
  • Fixed internal heat losses being factored into the displayed total external heat loss for projects with multiple floors.
  • Changed the default heated adjoining temperature to 15°C and the default unheated adjoining temperature to 5°C, per updates to the National Annex referred to in BS EN 12831-1 2017 and CIBSE. Previously they were 18°C and 10°C, respectively.
  • Fixed a bug where the ventilation heat loss was unexpectedly changing when an external wall material was changed, caused by certain walls not being counted as exposed facades.

​Why have my heat losses changed since the last time I opened the project?

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