EECN Buildings: The Path to Nearly Zero Energy Building

Spain is about to take a big step in energy efficiency within the construction sector. Starting in 2020, all homes or workplaces built in national territory must comply with the specifications of Nearly Zero Energy Buildings (EECN), a regulation that will make new constructions very different from those that have been built until now. But what does the emergence of EECN buildings imply?

This new construction will have many improvements aimed at energy efficiency and ensuring that the supplies needed indoors are minimal. For example, mechanical ventilation systems will be used, and there will also be a focus on alternative energy sources. Construction will also need to be highly airtight and have thermal insulation, and architecture will require designs that take advantage of natural light and solar energy. Everything must be integrated in the best way possible.

The obligation for EECN buildings is based on European directive 31/10/EU which governs Energy Efficiency in Buildings. This regulation marks a before and after in everything that governs construction, from planning and design to actual construction. Not surprisingly, one of the challenges of Nearly Zero Energy Building is its own architecture, although it also presents opportunities for the sector.

The Nearly Zero Energy Building imposes a new way of building, moving away from manufacturing cost savings and more focused on environmental respect and energy savings. Some of its bases are:

• Buildings must have a very high energy efficiency. The materials and ventilation systems must guarantee this supply saving, which should be almost total.
• User comfort must be ensured with comfortable indoor temperatures without the need for traditional air conditioning systems.
• CO2 emissions must be reduced to almost zero, as this is the main strategy of the European Union to combat climate change.

The problem in Spain is that, although the European regulation has been in place for a long time on a voluntary basis, there has been little commitment to Nearly Zero Energy Building, so the challenges for the immediate future of construction are significant. Since 2018, public buildings must adhere to European regulations, but the bulk of the sector is private construction, which will only be affected starting in 2020.

Fortunately, there are already constructions in our country and across Europe that follow regulations that comply with EECN buildings and even go beyond. For example, the certification seals BREEAM and Passivhaus are an easy way to adapt to the Nearly Zero Energy regulation with the guidelines of two regulatory milestones that have a lot of experience in the sector.

Requirements for EECN buildings

As previously discussed, EECN buildings seek minimum energy consumption and are governed by European regulations. However, in Spain, the conditions that must be followed are already included in the Technical Building Code (CTE), specifically in Basic Document HE.

To eliminate traditional air conditioning systems - which are the main contributors to high energy consumption indoors - it is necessary to implement a series of actions and construction processes. The main ones in Nearly Zero Energy Building are as follows:

1. Eco-friendly lighting. While all bulbs must be eco-friendly or of lower energy demand, the European EECN regulation proposes structural changes in lighting by promoting greater utilization of sunlight. Larger windows, well-studied orientation, and the use of automation systems to turn lights on and off, as well as regulate them depending on the specific moment.
2. Mechanical ventilation systems. In Nearly Zero Energy Building, it is specified that one-third of consumption must be allocated to ventilation, so its choice must maximize comfort at home. The most recommended option is double-flow mechanical ventilation, as it can climatize without the use of heating or air conditioning, thanks to heat recovery.
3. Thermal insulation. Construction materials must ensure that homes and workplaces do not allow cold or heat to pass through in winter and summer. This way, less conditioning is needed, which favors almost zero consumption.
4. Less conditioning. In addition to the ventilation system, other types of natural conditioning systems can be installed such as ventilated roofs and facades. We can install solar panels to avoid the need for supply energy.

Starting in 2020, EECN buildings will be a reality, so the sector must be prepared for a change that will undoubtedly be very drastic.