In brief
- From 1 October 2026 the rules name no source for degree days. You choose, and should say which.
- Figures from SMHI's paid Energiindex service may not be passed on, not even recalculated.
- SMHI's open data is free to use if you credit the source.
- A degree-day figure means nothing without two facts: the temperature it counts from and which years. Always ask for them.
On this page
What disappears
BEN named a source, albeit only in a general recommendation: "Energi för uppvärmning kan normalårskorrigeras med SMHI Energiindex (1981–2010)." That recommendation lapses. What remains is a bare functional requirement:
"The building's energy use shall reflect the energy use in an outdoor climate that is representative of a normal year for the locality where the building stands."
BFS 2026:9, 9 § — our translation
We searched the regulation in full. The words SMHI, graddag, energiindex and the years 1981, 1991 and 2020 do not appear once. No method, no normal period, no dataset. Stating which source you used therefore stops being a courtesy and becomes the precondition for anyone being able to check the figure.
Which sources exist
| Source | Cost | May it be passed on? |
|---|---|---|
| SMHI Energi-Index Graddagar, ort | 5 900 kr/yr | No — not even transformed |
| SMHI Energi-Index, hela landet | 55 000 kr/yr | No |
| SMHI öppna data (metobs) | 0 kr | Yes — CC-BY 4.0 |
| Typical-year files, SMHI/Boverket via Sveby | 0 kr | Unclear — no licence stated |
The free route, by contrast, is open. SMHI's open data sits under Creative Commons Attribution 4.0, with commercial use expressly permitted against attribution. Daily mean temperature is available for 941 stations, with a corrected archive going back decades. Alongside it sit 310 typical-year files — one per locality, normal period 1991–2020, produced by SMHI and paid for by Boverket — carrying both temperature and solar irradiance. Sveby states no licence for them, so ask before repackaging.
The definition has changed, and the figures with it
Until 2014 SMHI computed degree days at a base of 17 °C but with seasonal heating thresholds — 10 °C from May to July, 12 °C in April and September, 13 °C in October. From 2015 those thresholds were removed. Today's degree days are simply max(0, 17 − daily mean temperature).
The normal period has moved too: 1971–2000 → 1981–2010 (January 2015) → 1991–2020 (1 April 2022). The shift to 1991–2020 lowered calculated heating demand by 1–6 % and reflects a national mean-temperature rise of roughly 0.5 °C.
Degree days by locality, normal period 1991–2020
SMHI's normal-year degree days sit inside the paid product, so no free published table exists. The figures below are our own calculations from SMHI's and Boverket's typical-year files, at a 17 °C base without thresholds. An independent check against 30 years of station data from SMHI's open data agrees within ±4.3 %.
| Locality | Degree days | Legacy method | Mean temp | GHI kWh/m² |
|---|---|---|---|---|
| Malmö | 3 000 | 2 715 | 9,0 °C | 979 |
| Göteborg | 3 195 | 2 949 | 8,5 °C | 977 |
| Stockholm | 3 594 | 3 349 | 7,4 °C | 1 000 |
| Örebro | 3 752 | 3 469 | 7,0 °C | 951 |
| Karlstad | 3 779 | 3 502 | 6,8 °C | 960 |
| Sundsvall | 4 498 | 4 219 | 4,7 °C | 890 |
| Umeå | 4 779 | 4 499 | 3,9 °C | 824 |
| Luleå | 5 242 | 5 002 | 2,7 °C | 841 |
| Kiruna | 6 377 | 6 202 | −0,4 °C | 693 |
The climate zones are gone
The I–IV zones were abolished back in 2017 by BFS 2017:5 and replaced with a geographic adjustment factor per municipality. BFS 2026:9 keeps the factor but moves it out of the formula and into the limit values, and carries a recomputed table for all 290 municipalities in the range 0.8–1.8. It differs from BBR's: Kiruna goes from 1.9 to 1.8, Sundsvall from 1.3 to 1.2, Boden from 1.5 to 1.6. If the factor is hard-coded, two tables are needed, chosen by date.
Sources and caveats
Sources and caveats. BFS 2026:9 · BFS 2016:12 (BEN) and BFS 2017:6 (BEN 2) · BFS 2017:5 (BBR 25) · BFS 2024:14 (BBR 31) · SMHI's 2026 energy-efficiency price list · SMHI open data, metobs, CC-BY 4.0 · the 1991–2020 typical-year files from SMHI and Boverket via Sveby. The degree-day figures are computed by us from official inputs, not taken from a published table. The method is SMHI's current definition. The licence position for the typical-year files is unconfirmed.