Lighting in Nearly Zero-Energy Buildings
With the aim of implementing the 2030 Agenda for Sustainable Development of the United Nations, the European Union has set a series of actions realised in different regulations. One of the most important is the Energy Efficiency Directive (EED), which advocates for member states to transition towards a system in which sustainability is key, without neglecting competitiveness and safety.
The EED issued in 2012 so that EU members implemented measures to improve energy efficiency in several areas was initially aimed at improving efficiency by 20% by 2020. However, the EED was revised in 2018 (2018/2002) and this goal was set at a minimum of 32.5% by 2030.
Nearly zero-energy buildings in the EU's sustainable development plan
According to EU data, buildings represent 40% of the total energy consumption in Europe. Therefore, the EED includes a fundamental concept that has become a priority goal: the nearly zero-energy buildings (nZEB).
This is a building model whose net energy consumption in a typical year is close to zero. To achieve this, measures have to be taken to help improve the efficiency or energy performance of buildings, which refers to the amount of energy needed to cover the demand for the use of the building, including components such as heating, air conditioning, ventilation, water heating and lighting. A nZEB's consumption equals its demand and, in addition, uses mainly renewable power supplies.
The EU intends to promote the renovation of all European buildings to comply with the EED and require new buildings to be nZEB as of 2020 (2018 for public buildings).
Sustainable design criteria
When talking about designing a building while trying to ensure efficient consumption, the aim is to design and construct buildings that do not consume more than needed, and this premise has to be taken into account from the inception and conceptualisation of any project.
In the words of Ricard Santamaría, director of the building project management company H.A.U.S HEALTHY BUILDINGS, when starting a project 'the first item to be discussed is demand, it seems clear that the first outline of a project has to be done with an unequivocal intention, to set the energy demand at the minimum levels possible.' Achieving a minimum energy demand must be one of the cornerstones of the project: 'If low demand levels are achieved, much has been already done..., then that demand will be solved with efficient systems powered by renewable energies, but zero demand is the driving force of the project,' concludes Ricard Santamaría.
This energy savings are absolutely necessary to achieve the Sustainable Development Goals set by the UN and the EU, and also represent a significant economic saving for the end user.
The main pillars of a low energy demand building are:
- A climate study on the environment and location taking into account the different hygrothermal variables: temperature, moisture, solar radiation, wind speed and direction, among others;
- Setting out 'passive' strategies to reduce energy demand by incorporating them into the building's design;
- Correct thermal management and adequate ventilation through 'passive' strategies to reduce energy demand, and subsequently searching and proposing the most efficient active ventilation solutions and air conditioning systems;
- Analysis and proposal of local energy sources and resources so as to obtain as much of the necessary energy as possible from renewable sources, minimising the use of fossil energies with maximum efficiency criteria.
With regard to lighting, it is very important to prioritise natural lighting and find the correct complements in artificial lighting.
Artificial lighting in nZEB buildings
Power consumption is defined as the relationship between the building's energy needs and the performance of the equipment and facilities. This is where lighting comes into play, becoming one of the key factors in the equation.
The Spanish Technical Building Code (CTE) dictates the limitation of energy consumption by establishing maximum values of VEEI (Energy Efficiency Value of the Installation) according to the properties of the building and the weather conditions, as well as the activity for which it is intended.
In this sense, the generalisation of the use of LED technology has been of great help, as this technology entailed a great reduction of energy consumption, achieving energy savings of up to 80% compared to other technologies, according to data from the US Department of Energy.
However, efficient light sources are not enough, it is also necessary to determine energy consumption control and monitoring systems to ensure greater efficiency. To this end, systems for the use of natural light and the control and regulation of artificial lighting are implemented, regulating the luminous flux of the luminaires through manual switching and control systems, timers or even the latest ones based on wireless technologies for remote control.
Merging concepts of sustainability and well-being
However, it is 2021 and it is necessary to expand the conversation beyond the creation of efficient spaces to also contextualise and humanise these solutions under the paradigm of sustainability linked to user well-being.
From the point of view of the visual effects of lighting, the lighting solutions provided must guarantee:
- The illuminance level required for the task to be performed;
- Strategies of contrast and adequate uniformity to create comfortable spaces, where the data related to the finishes that make up the space are very important for an adequate calculation of the luminances;
- Low levels of glare, allowing users to carry out their work without discomfort;
- Suppression of the 'flicker' effect that can cause undesirable effects such as reduced visual comfort and task performance, even leading to physiological effects such as fatigue or headaches;
- Adequate chromatic reproduction for the task to be performed, among others.
Current contrasted studies show that, besides visual effects, lighting has non-visual effects on human beings, which must be taken into account when choosing a suitable light source. Therefore, it is important to determine the following parameters:
- The proper ratio of lighting level (illuminance, measured in lux) and correct colour temperature (measured in Kelvin degrees), taking into account the project's geographical and cultural context;
- Optimal spectral power distribution to improve circadian activation, while taking into account the optimisation to a 480 nm emission wavelength, which has been scientifically proven to have an impact on our circadian cycle;
- Design of light itineraries and scenes that allow users to have dynamic lighting solutions that adapt to their functional needs, but also from a biological and emotional point of view.