What are nearly zero energy buildings? (I)

According to the application guide of the updated Basic Document on Energy Saving (DB-HE) of the CTE on which this blog post is based, a dwelling or building with almost zero energy consumption is defined as one that meets the regulatory requirements established in the updated document, DB-HE, in reference to the limitation of energy consumption for newly constructed buildings. To this end, it sets and quantifies maximum Primary Energy consumption values both at a total level and in relation to its non-renewable origin. But to understand these values, it is first necessary to be clear about the concept of Final Energy, total Primary Energy (PE) and those derived from its origin: renewable and non-renewable PE.

Energy Basics:

• Final Energy: It is the energy that is supplied to the buildings, it can be transported in different ways, called energy vectors: electricity, natural gas, biomass, etc. Thus, the Final Energy is that which is measured and supplied at the entrance of the dwellings, in our case, at the entrance of the new dwellings in Gandia of the MarPlus Residential Estate.
• Primary EnergyFinal Energy: This is what is actually needed to supply the Final Energy. That is to say, from the energy of nature, after a series of losses in the intermediate processes of transformation, transport or distribution, a Final Energy (FE) arrives at the dwelling, which will always be lower than the Primary Energy actually required. In order to find out the rate of PE used to obtain a FE, the so called pass factorsThese depend, among other things, on the energy vector used or its origin. Thus, for example, for the electricity obtained from the grid, in a general way, a step factor of 2.36kW-h could be estimated, i.e. to obtain 1kW-h of FE, a total of 2.36kW-h would have had to be extracted from nature, of which a part could have come from a renewable source and another from a non-renewable one:
  • Renewable or non-renewable EP: Primary energy can be classified depending on its origin. Although it always comes from nature, it can come from renewable or non-renewable sources. For example, in the specific case of electricity, it could have been generated at source by a photovoltaic solar panel plant or in a thermal power station. In the first case, it is a renewable source and in the second case it uses a fossil fuel that is obviously not renewable.

Once these basic concepts are known, we can understand why the standard is based on PE and its type of origin, and not simply on the final energy consumed. In this way, the energy resources used, their renewable or non-renewable nature, can be truly assessed and thus used to compare the efficiency of different buildings in relation to each other.

Nearly Zero Primary Energy Consumption Building:

Returning to the initial question, the DB-HE in its chapter HE0 which focuses on the limitation of energy consumption, sets the same for a new construction as is the case of the Residential MarPlus, in the winter climate zone defined as B and, according to table 3.1a to those who have a limit value of non-renewable EP consumption not exceeding 28kW-h/m2-yr and also, according to table 3.2a, have a limit value of Total EP consumption not exceeding 56kW-h/m2-yr.
Our new building in Gandia, the Residential MarPlus, complies with these requirements obtaining values well below the required values as we will explain in future blog entries, where the other chapters of the DB-HE will be taken into consideration.

Visit the home page of our website https://ganditec.es to have access to all the documentation of our new development next to the beach of Gandia. New housing in Gandia, in la Safor, the Residencial MarPlus.