Lights and shadows of the new building efficiency standard

On December 28, the new regulation that modifies the Technical Building Code (CTE), with new requirements included in three basic documents (Energy Saving, Health and Safety in case of Fire) aimed at improving energy efficiency, entered into force of buildings and ensure the health, comfort and safety of people. Subscribe for free to the Economist Energy

The new regulations will be mandatory from next June 28 for new construction works and interventions in existing buildings – extensions, changes of use, reforms – for which a municipal building license is requested.

The publication of the CTE has been well received in the sector, which had long been waiting for an adequate framework that regulates the necessary aspects aimed at achieving more sustainable and environmentally friendly homes, in order to achieve the decarbonization of the Spanish building park in 2050.

In the opinion of the Association of Manufacturers of Heat Generators and Emitters (Fegeca) – shared, in general, by all the actors in the energy efficiency sector – the modification of the CTE is “a turning point in the market of the building, marking the limits of energy consumption of buildings, which should be more sustainable and with greater importance of renewable energy sources. ”

Although the sector qualifies these changes as “positive” and “beneficial”, some entities and associations that integrate it think that “they are not enough” and that they could have been “more demanding” in some parameters, especially if we consider that the building sector, as indicated by the Association of Energy Efficiency Companies (A3e), “is the third in energy consumption in the country. In addition, more than half of Spanish homes (about 60%) were built without no energy efficiency regulations, so there is great potential for improvement in the renovation of the real estate park. “

Although, on the one hand, the term Almost Null Energy Consumption Building (nZEB) is included, a definition of how a building of these characteristics, whether new or rehabilitated, that includes numerical values ​​of consumption and the origin of the energy to use. Likewise, the Regulation of Thermal Installations of Buildings (Rite) is not updated, “which leaves thermal installations without requirements that would help, to a large extent, to achieve nZEBs,” they point out from A3e. Nor have there been changes in building lighting.

Promotion of renewables and improvements in the envelope

Regarding the new Basic Energy Saving Document (DB-HE), its review “implies a very important structural change for tertiary buildings, going from a self-referential check to an absolute comparison of the building's energy efficiency,” they point out from the Association Spanish Air Conditioning and Refrigeration Technique (Atecyr). In this way, they add, “it is sought that the energy consumption of new construction homes does not exceed the thresholds between 40 to 86 kWh of primary energy per square meter useful of the homes in a reference year. In the case of interventions in buildings, these thresholds are between 55 and 115 kWh of primary energy consumption. ”

One of the new requirements of the DB-HE is that energy consumption is satisfied, to a large extent, using energy from renewable sources. Based on this, as explained by the Association of Manufacturers of Air Conditioning Equipment (Afec), “the indicator of non-renewable primary energy consumption (Cep, nren) is maintained, encouraging the use of equipment that uses renewable energy to to achieve the required results, and incorporates a new indicator relative to the total primary energy consumption (Cep, tot) “, which replaces the levels of limit heating and cooling demand.

Another of the key points is the improvement of the quality of the thermal envelope in order to control the energy demand of the building, which will limit the needs of primary energy and prevent decompensation in buildings of any use, thus avoiding unwanted energy losses. In this line, as explained by the National Association of Energy Services Companies (Anese), “much higher thermal transmittance requirements are introduced (the increase in demand ranges from 5% to 40%, depending on the climatic zone of winter to analyze and the constructive element), which implies a decrease of the losses and gains of heat of the envelope, thus increasing the energy efficiency of the building “.

The change in the envelope of the building, explained from the Superior Council of the Colleges of Architects of Spain (CSCAE), “is especially positive because elements and conditions are introduced that allow us to work with the envelope in a more versatile way, without separating systems , as until now, but considering the building as only the architects do it: as a set on which one must work in a holistic and transversal way “. From now on, they add, “it goes from being a sum of things, with a doubtful relationship between them, to moving towards a more realistic understanding of what separates the inside from the outside, like a skin, with joint behaviors.”

Thanks to the update of the Technical Building Code, it will be possible “a more sustainable building, in which the role of architects will be more relevant than ever, since, from the beginning of the project, the shape, volume and exposure solar, will be determinants to improve the energy efficiency of buildings in an integral way “, they point out from the CSCAE.

ACS demand coverage

Another of the most relevant developments included in the DB-HE is that there is no longer talk of a minimum solar contribution of domestic hot water, but a minimum contribution of renewable energy to meet the demand for domestic hot water, which opens the scope to all the energies from renewable sources, leaving open the range of possibilities to use other types of technologies, so that the buildings will meet their needs for ACS and pool heating using, to a large extent, clean energy or renewable cogeneration processes, well generated in the building itself or through the connection to an urban heating system. It also allows the recovery of residual energy from cooling equipment in residential buildings.

In this line, it establishes that the minimum contribution of energy from renewable sources will cover at least 70% of the annual energy demand for ACS and pool heating, obtained from the monthly values ​​and including thermal losses by distribution, accumulation and recirculation. This minimum contribution will be reduced to 60% when the demand for ACS is less than 5,000 l / d.

In the case of heat pumps intended for the production of DHW and / or pool heating, it is established that, in order to consider their renewable contribution, they must have a seasonal average yield value (SCOPdhw) of more than 2.5 when they are electrically operated and higher than 1.15 when they are powered by thermal energy. This value shall be determined for the ACS preparation temperature, which shall not be less than 45 ° C.

Section 5 of the DB-HE focuses on the minimum generation of electrical energy, which requires the incorporation of electrical energy generation systems from renewable sources for own use or supply to the network, both in newly constructed buildings and extensions of existing buildings and those that are largely or completely reformed, where the constructed, modified or renovated area exceeds 3,000 m2, “expanding the previous scenario set at 5,000 m2,” indicate from Anese. In addition, the mandatory power to be installed may not be less than 30 kW or exceed 100 kW.

Another of the basic documents that make up the new Technical Building Code is that of people's health (DB-HS). The most novel thing is the incorporation of the protection of the real estate against exposure to radon gas, both in the justifying parameters of the project and in the control measures in the buildings constructed. To reduce possible risks to people's health, municipalities with high concentrations of radon are identified, a reference level is established for the concentration of this gas inside the habitable premises and the protection of buildings is defined according to of the risk associated with the municipal term.

Finally, the document on Fire Safety (DB-SI), limits the risk of propagation outside the building, since it incorporates a punctual modification that raises the demands on facade materials in buildings of more than 28 meters high and also includes the regulation of these elements in buildings up to 18 meters. It is improved, in general, to prevent drops and particles falling from the façade, chamber and roofs for all sections of height.