From A to E
A · mildest winterE · coldest winter
It reflects heating and cold-side insulation needs. A stands for mild winters (Mediterranean coast, Canary Islands); E, for the harshest ones (high mountains, inland plateaus).
Technical reference / Climate_01
The climate zone decides how much energy can be certified.
Before calculating a saving, the action has to be placed in the climate where it happens. The climate zone sets the starting conditions — winter cold, summer heat — and with them the saving one same measure can evidence in a CAE application. Framework: CTE DB-HE, Annex B. CAE application: RD 36/2023 and Order TED/845/2023.
NOTE
What a climate zone is
The Spanish Technical Building Code splits the country into climate zones to describe, in a standardised way, the thermal demand of each location. It is not an administrative label: it is the figure that governs a building's energy calculations.
Each zone has a two-character code: a letter and a number. The letter describes how much cold must be overcome in winter; the number, how much heat must be removed in summer.
Two identical buildings in Almería and Burgos do not consume the same energy, nor do they produce the same saving once upgraded. The climate zone makes that difference visible.
HOW TO READ IT
A letter for winter, a number for summer
Of the 20 possible combinations, only some occur across the territory. Select a zone in the matrix to see its character and reference cities.
From 1 to 4
1 · coolest summer4 · hottest summer
It reflects cooling and solar-protection needs. 1 stands for mild summers (Cantabrian coast, high mountains); 4, for the most extreme ones (Guadalquivir valley, south-east).
Example — Madrid is D3: cold winter, hot summer. Málaga is A3: mild winter, warm summer.
The zones that actually exist
Winter ↓ · Summer →
1234ABCDE
Winter in rows (A–E), summer in columns (1–4).
About the Canary Islands. At low altitude the islands add zone α (alpha), with winters even milder than A. In the Canary capitals, common practice uses a reference close to A3, adjusted by altitude under Annex B.
PROCESS
Province and altitude, not intuition
A location's zone is not picked by eye. It comes from the Annex B table of the DB-HE, crossing the province with the altitude above sea level.
Provincial capital
Start from the zone assigned to the capital of the province where the action takes place. That is the table's reference point.
Altitude correction
The zone is adjusted by the altitude difference between the location and the capital. Higher altitude usually hardens the winter (letter towards E).
Resulting zone
The crossing gives the final zone. That is the value documented and used as the basis for the application's calculations.
One municipality can fall into two zones when its territory spans very different altitudes. The figure is therefore justified with the plot's real altitude, not the town centre's by default.
QUICK REFERENCE
Climate zone of provincial capitals
Indicative reference values for the capitals at their reference altitude. For a specific location, the zone is confirmed with the Annex B table and the plot's altitude.
| City | Zone | Character |
|---|---|---|
| Madrid | D3 | Cold winter, hot summer |
| Barcelona | C2 | Moderate winter, temperate summer |
| Valencia | B3 | Mild winter, warm summer |
| Sevilla | B4 | Mild winter, very hot summer |
| Zaragoza | D3 | Cold winter, hot summer |
| Málaga | A3 | Very mild winter, warm summer |
| Murcia | B3 | Mild winter, warm summer |
| Palma | B3 | Mild winter, warm summer |
| Bilbao | C1 | Moderate winter, cool summer |
| Alicante | B3 | Mild winter, warm summer |
| Valladolid | D2 | Cold winter, temperate summer |
| Vigo | C2 | Moderate winter, temperate summer |
| Granada | C3 | Moderate winter, warm summer |
| A Coruña | C1 | Moderate winter, cool summer |
| Pamplona | D1 | Cold winter, cool summer |
| Almería | A4 | Very mild winter, very hot summer |
| Córdoba | B4 | Mild winter, very hot summer |
| Toledo | C4 | Moderate winter, very hot summer |
| Badajoz | C4 | Moderate winter, very hot summer |
| Santander | C1 | Moderate winter, cool summer |
| Salamanca | D2 | Cold winter, temperate summer |
| Burgos | E1 | Very cold winter, cool summer |
| Ávila | E1 | Very cold winter, cool summer |
| León | E1 | Very cold winter, cool summer |
| Las Palmas | A3 | Very mild winter, warm summer |
| S. C. de Tenerife | A3 | Very mild winter, warm summer |
NOTE
The climate zone enters the CAE calculation
The Energy Savings Certificates system (RD 36/2023) recognises savings through the sheets of the standardised measures catalogue (Order TED/845/2023). Each sheet sets its scope, calculation formula and required documentation.
Many of those formulas depend on climate. The sheets include technical annexes — among them values per climate zone — that feed the annual saving calculation. Changing the zone changes those parameters and therefore the energy evidenced.
The practical consequence: the same equipment replacement or envelope upgrade does not perform the same in B3 as in E1. Getting the zone right is not a preliminary formality; it is part of the certifiable saving itself.
SCENARIOS
Sensitivity to the climate zone
Indicative weight of the zone in the calculation, by family of measure.
Envelope insulation
The saving depends directly on the location's heating and cooling demand.
High sensitivity
Windows and joinery
Same principle as the envelope: the zone sets the reference temperature gap.
High sensitivity
HVAC (heat pump)
Seasonal performance and running hours change with the zone's climate.
High sensitivity
Ventilation with heat recovery
Heat recovery performs better where the indoor-outdoor gap is larger.
Medium sensitivity
Solar thermal / DHW
Driven more by available radiation than by winter or summer severity.
Medium sensitivity
Efficient lighting
The saving rests on power and hours of use; climate has little influence.
Low sensitivity
FAQ
Frequently asked questions
01How do I know which climate zone my project is in?
It is determined with the Annex B table of the DB-HE, crossing the provincial capital with the plot's real altitude. The capitals table on this page is indicative.
02Why does the zone change the certifiable saving?
Many CAE catalogue sheets include climate parameters in their formula. Changing the zone changes those parameters and therefore the annual saving evidenced.
03Can one municipality have two zones?
Yes. When its territory spans very different altitudes, the altitude correction can place two locations of the same municipality in different zones.
NOTE
Methodological note
This page summarises the reference framework. The zone applicable to each application is set case by case, with verifiable criteria.
The zone comes from Annex B of the DB-HE, crossing province and plot altitude. Capital values are indicative and may be adjusted by altitude or other local conditions.
The final saving depends on the applicable sheet, its climate parameters and the quality of the documentation. No estimate replaces the verification and validation set out in the CAE system.
NEXT STEP
Submit a projectDo you know which zone your project is in?
With the location and technical data, we check the applicable climate zone and whether the documentary basis is enough to build the application.