Under UNE-EN ISO 52120-1, as used by Spain’s MITECO in its savings sheets, moving from standard control (class C) to advanced control (class B) saves a home 12 % on heating and cooling and 10 % on hot water; reaching class A raises savings to 19 % and 20 %. In offices, hotels or shops the percentages are higher, and lighting also counts.
The four efficiency classes
| Class | Level | What it means in practice |
|---|---|---|
| D | Low efficiency | No efficient control: manual on/off. |
| C | Standard (reference) | Thermostat and basic schedules. |
| B | Advanced | Zone or room control, schedules, presence and central monitoring. |
| A | High efficiency | Demand and occupancy control, coordination between systems and continuous optimisation. |
Savings in a home
Percentages calculated with the factors in MITECO sheet RES040 and rounded. The residential sheet does not include lighting.
| Service | C to B | C to A | D to B | D to A |
|---|---|---|---|---|
| Heating and cooling | 12 % | 19 % | 19 % | 26 % |
| Domestic hot water | 10 % | 20 % | 19 % | 28 % |
Savings in tertiary buildings
Percentages calculated with the factors in MITECO sheet TER050. A dash means the standard assigns no saving to that class change.
| Building type | Heating | Cooling | Lighting |
|---|---|---|---|
| Offices | 30 % | 43 % | 28 % |
| Hotels | 39 % | 24 % | 24 % |
| Restaurants | 31 % | 40 % | — |
| Retail | 54 % (highly ventilation-dependent) | 45 % | — |
What to automate to reach class B
- Climate control by room or zone, not a single thermostat.
- Schedules and away modes, and switch-off with windows open.
- Hot water control by schedule and temperature.
- In tertiary buildings, presence-detected lighting dimmed to daylight.
- Central monitoring to detect abnormal consumption.
Energy savings certificates
Projects that bring a service to at least class B can certify the savings through Spain’s energy savings certificate scheme (CAE), using sheets RES040 or TER050. Among other documents, they need a post-project energy performance certificate, invoices and the installer’s BAC class declaration.
Home automation energy savings calculator
Estimate how much you can save by automating heating, cooling, hot water and lighting, using the official UNE-EN ISO 52120-1 factors that Spain’s Ministry uses for energy savings certificates.
- Estimated annual savings
- Of the spend entered
- Payback
| Service | Spend | Savings | % |
|---|
Indicative estimate based on the UNE-EN ISO 52120-1:2022 efficiency factors included by Spain’s Ministry (MITECO) in CAE sheets RES040 and TER050. Actual savings depend on the building, equipment and use.