3 August 2020
Requirements for nearly zero-energy classification
Nearly zero-energy buildings represent one of architecture’s hottest trends today. In order to be eligible for nearly zero-energy status, buildings have to comply with a complex set of criteria concerning overall energy performance. This regulatory framework specifies the types of both structural elements and MEP systems to be used when realising such buildings.
In line with its status as an EU member state, Hungary introduced requirements pertaining to nearly zero-energy buildings (or NZEBs), effective from 1 January 2016. Following 1 January 2021, new buildings and buildings undergoing comprehensive renovation will not be eligible for an occupancy permit unless they are granted a BB energy certificate or higher. Crucially, the date the be considered here is not the one on the building permit or the simple notification, but rather the starting date of occupancy. In case the designer is not meticulous enough, the building might not meet the requirements for a “BB” certificate, and the relevant authority will deny issuing the occupancy permit.
Design factors to take into account
In terms of energy, the design process is a rather complex task: besides adequate thermal insulation for each and every structural component, the designer must draw up MEP systems with the utmost care. In Hungary, technical conditions for nearly zero-energy classification are stipulated in Ministerial Decree 7/2006. (V. 24.).
The aforementioned decree specifies the minimum thermal insulation characteristics of all newly-installed building materials, structural components, as well as doors and windows.
Criteria for nearly-zero energy level also cover energy carriers used in the buildings – for instance, whether we rely on gas, firewood or district heating for the purposes of space heating and water heating. In order to meet nearly-zero energy requirements, renewable sources have to account for at least 25% of overall energy consumption. In practice, this means that failing to ensure a 25% renewable energy ratio will certainly result in a lower, “CC” certification, even if other indicators would be sufficient for a higher rating.
The following renewable energy carriers can be taken into consideration: firewood, biomass, energy generated directly or indirectly from biomass, biogas energy, wood pellets, biopellets, solar energy, wind energy, hydropower, geothermic and geothermal energy, hydrothermal energy, air thermal energy, and – with certain restrictions – district heating.
Generally, relying on heat pumps or solar panels is the easiest way to meet the requirements. Ensuring sufficient space for MEP systems is key in the design stage: for instance, retrofitting a building with a heat pump system would be a complicated undertaking.
In order to guarantee the desired classification, we make preliminary calculations in the design phase, because proper building orientation will have an effect on the rating, similarly to the ratio of gross heated volume and cool surfaces. By preparing the calculations simultaneously with the designs, we are able to avoid any surprises concerning the occupancy permit.