About U Value Studio
U Value Studio is a calculator for wall, roof and floor build-ups. Build a construction layer by layer and see its U-value, whether it meets your local building regulations, and its risk of condensation inside the construction, with a 3D view and a PDF report.
It's built for architects, retrofit coordinators and designers, building surveyors, energy assessors, and anyone else who needs to get these numbers right first time, not just a rough estimate.
The regulation checks are verified against the official regulations and guidance for 11 territories: England, Scotland, Wales, Northern Ireland, Ireland, Germany (GModG), France (RT Existant/RE2020), the US (IECC), Canada (NBC 9.36), and Australia (NCC Part 13.2, mainland and Northern Territory benchmarked separately). U-values follow BS EN ISO 6946 throughout. Condensation is checked two ways in every territory: a quick design-condition check and a month-by-month moisture balance (BS EN ISO 13788). In the UK and Ireland, Advanced mode adds a long-term moisture check, hour by hour with real local weather.
Why U Value Studio
Each country's own rules. Every territory is checked the way its own regulations work, from per-element U-value limits in the UK and Ireland to climate zones in the US and Canada. Figures taken directly from an official source are shown as such, and any that are approximations are clearly flagged.
It doesn't skip the hard parts. Ground floors (BS EN ISO 13370:2017), condensation risk with the amount that builds up in g/m² a day, a monthly moisture balance (BS EN ISO 13788) that tracks whether any condensation dries out again over the year, and dynamic thermal response (decrement factor, time lag) for summer overheating: the points where simpler calculators usually stop.
A long-term moisture check (beta), in Advanced mode. For the UK and the Republic of Ireland it follows heat and moisture through a build-up hour by hour for 3 or 5 years with real Met Office and Met Éireann weather, with moisture stored in the materials, liquid movement, rain and sun, following the calculation method of BS EN 15026:2023. It can run on a single build-up or on every wall and roof slope of a simple house at once. The solver passes the benchmark test in BS EN 15026:2023 (Annex B) and has been checked against HAMSTAD benchmarks 1, 2, 4 and 5. It is a screening check, not a replacement for the regulatory methods or a full hygrothermal study.
Visual and shareable, not just a number. An interactive 3D view with material-accurate colours that shows where the framing bridges the insulation, plus a PDF report you can attach to project documentation, with the assumptions and sources listed.
Real products as well as generic materials. The materials library includes real products from manufacturers' datasheets alongside standard generic values, so you can model the specific product you've specified.
Sources and editions
The calculation methods and the regulatory benchmarks are checked against these editions. We last reviewed them in November 2026, and update them as new editions come into force.
Calculation methods. BS EN ISO 6946:2017 (U-values), BS EN ISO 13788:2012 (condensation), BS EN ISO 13370:2017 (ground floors), BS EN ISO 13786:2017 (dynamic thermal response), BS EN ISO 10456:2007 (material properties), BS EN 15026:2023 (long-term moisture check) and BS 5250:2021 (moisture in buildings).
Weather for the long-term moisture check. Real hourly observations from 16 Met Office stations across the UK (MIDAS Open, via the Centre for Environmental Data Analysis) and 8 Met Éireann stations across the Republic of Ireland, using each station’s second wettest year by driving rain from its complete years of 2011 to 2025. UK data: MIDAS Open hourly weather observation, hourly rainfall and hourly solar radiation data, version 202607; contains public sector information licensed under the Open Government Licence v3.0; © Crown copyright, Met Office. Irish data: Met Éireann hourly and daily station data, licensed under Creative Commons Attribution 4.0; copyright Met Éireann, source www.met.ie; the Irish stations don’t measure solar radiation hourly, so U Value Studio works it out from their sunshine and cloud readings, calibrated against and, at Dublin Airport, scaled to the daily radiation measured there. Met Éireann does not accept any liability for any error or omission in the data, their availability, or for any loss or damage arising from their use. U Value Studio converted the units and filled short gaps; neither the Met Office nor Met Éireann endorses this tool or the choice of year.
| Territory | Edition used | Note |
|---|---|---|
| England | Approved Document L, Volume 1: Dwellings, 2021 edition incorporating 2023 amendments | The 2026 edition (Future Homes Standard) is not in force until 24 March 2027. |
| Scotland | Technical Handbook (Domestic), April 2026 edition | Section 6, Table 6.2. |
| Wales | Approved Document L (Wales) 2022, incorporating 2024 amendments | A new edition takes effect on 4 March 2027. |
| Northern Ireland | Technical Booklet F1: 2022 | |
| Ireland | Technical Guidance Document L (Dwellings) 2022 | A 2025 revision has been consulted on but is not yet in force. |
| Germany | DIN 4108-2 (minimum thermal protection) and DIN 4108-3:2024-03 (condensation) | DIN 4108-2 was reissued in May 2026. The minimum values used are believed unchanged, and are being confirmed against the new text. |
| France | RT existant par element (arrete of 2007 as amended in 2017, in force from 1 January 2023) | |
| USA | IECC 2021, Table R402.1.2 | Adoption varies by state. |
| Canada | National Building Code of Canada 2020, Part 9 (Section 9.36) | Confirmed unchanged for Part 9 in the 2025 edition. |
| Australia | NCC 2022 Amendment 2, Part 13.2 (Energy efficiency), carried forward unchanged in NCC 2025 | The Northern Territory is benchmarked separately and remains on NCC 2022. |
Always confirm the edition that applies to your project and location, since adoption dates differ and local amendments exist. Results support, and do not replace, the judgement of a competent person.
A note on scope
The design-condition and monthly condensation checks follow the simplified methods in the standards and leave out some effects, such as rain, sun and moisture stored in the materials. The long-term moisture check includes these, but it is a screening check, not a full hygrothermal study. Results are a starting point for a competent person's review, not a certified assessment.