Despite some obstacles to wider adoption, the advancement of smart buildings is being promoted at the European level through the Energy Performance of Buildings Directive (EPBD). Additionally, several European projects are tackling these challenges through innovative solutions.
(Note: Opinions in the article are of the authors only and do not necessarily reflect the opinion of the European Union)
Introduction
Article 1 of the revised Energy Performance of Buildings Directive (EPBD) (EU/2024/1275) outlines its objective: to promote practices that achieve a zero-emission building stock in the Union by 2050. This goal is based on a set of criteria that consider climatic conditions, adequate indoor environmental quality standards, and cost optimisation.
The article further specifies the areas where the directive sets out requirements. These include national building renovation plans, inspections of heating, ventilation and air-conditioning systems, the integration of solar energy, and a general framework for calculating energy efficiency.
The list could go on, reflecting the complexity involved in decarbonising the building sector.
In this overview article, however, we will focus on smart buildings – which is precisely one of the key areas of intervention outlined in the first Article of the Directive.
So, what makes a building smart?
To merit this designation, a building must be capable ‘of sensing, interpreting, communicating, and actively responding to changing conditions related to building systems or the external environment (e.g., energy grids)’. These characteristics enable the building to reduce energy waste by optimising efficiency while improving indoor environmental conditions. Improved energy efficiency also results in lower energy bills. It’s due to these qualities that smart buildings fall within the EPBD's areas of interest, by responding to the criteria outlined in Article 1.
In general, for a building to ‘behave’ in this way, it must be equipped with sensors, controllers, software, and user interfaces that work together to monitor conditions and optimise resource use to maintain appropriate environmental conditions. This combination of technologies is commonly referred to as Building Automation and Control Systems (BACS).
BACS therefore automates processes previously managed by the user, regulating various home systems, including temperature and lighting control. Precisely, the European standard EN 15232 identifies seven BACS control macro-functions:
heating control
domestic hot water (DHW) control
cooling control
ventilation and air conditioning control
lighting control
blind control
technical home and building management
Cutting-edge technologies in this field stem from the Internet of Things (IoT), which generally involves sensors capable of communicating and exchanging data over a network, and Artificial Intelligence (AI), used, for example, in algorithms that control heating, ventilation, and air conditioning (HVAC) systems. These algorithms enable self-learning behaviour based on users' patterns and needs, potentially leading to energy savings of up to 40%.
Success stories and prospects
Annex 81 of the International Energy Agency’s Energy in Buildings and Communities (IEA EBC) programme is dedicated to data-driven smart buildings. The project ‘imagines a future world empowered by access to discoverable, reliable, ubiquitous real-time data from buildings, such that digital solutions can rapidly scale and where energy efficiency knowledge can be widely encapsulated and disseminated within highly accessible software “Applications”’.
Other objectives of the project include disseminating significant results through case studies presented on a dedicated website. These cases, covering both residential and non-residential buildings in Europe, Asia, Australia, and North America, demonstrate the ability of smart technologies to enhance energy efficiency and indoor environmental quality.
One such example is TU Delft Building 28, a living laboratory within the Brains 4 Building project (2021–2025), funded by the Dutch Ministry of Economic Affairs & Climate. Renovated in 2018 to achieve energy class A, this highly efficient building is testing a key smart technology to minimise energy consumption and wastage: an algorithm for automated fault detection and diagnostics (FDD) in HVAC systems, applying the 4S3F method.
Figure 1. TU Delft Building 28.
Another example is the Horizon 2020 EXCESS project which aims to demonstrate how nearly zero-energy buildings (nZEBs) can be transformed into plus-energy buildings (PEBs). The project currently features four demo cases in Austria, Belgium, Finland, and Spain.
To achieve PEB status, a building is likely to incorporate some level of smart technology. For example, in the Finnish case, alongside various features that enhance sustainability - such as a geothermal energy well for heating and cooling, as well as energy-generating façades - there is an optimisation algorithm that predicts energy production based on atmospheric conditions. This algorithm also considers energy price trends, adjusts consumption intelligently, and dynamically interacts with the grid by selling excess energy and purchasing it when needed, thereby optimising both costs and sustainability.
Figure 2. The EXCESS PEB being developed in Helsinki. Credits: EXCESS.
Finally, we mention the Horizon Europe project BuildON. BuildON aims to decarbonise buildings through digitalisation and automation. It will test its technologies in six case studies across Europe: a residential building in Spain, another in Finland, a kindergarten in Poland, an office building in France, and two commercial buildings in Greece.
For example, the Spanish case features a 2018-renovated building with smart radiator valves for autonomous temperature adjustment and AI-driven analysis to optimise heating, electricity use, and second-life battery management. The building will also be equipped with a digital twin to simulate energy improvements before applying them in real life.
Figure 3. The BuildON’s demo case in Valladolid (Spain). Credits: BuildON.
Current challenges
Investing in smart technologies and ensuring their proper integration is often considered cost-effective, with a short return on investment (ROI), particularly in the tertiary sector.
However, several practical challenges remain:
the prevalence of proprietary standards, which makes it difficult to integrate products from different manufacturers, thus hindering interoperability
the significant differences between residential and commercial sector products leading to integration, cost and scalability issues
the short lifespan of many components, which are often non-replaceable
A key challenge in AI deployment is developing lightweight, specialised models that train locally on received data, preserving privacy while enabling collaboration across devices and cloud services.
EU policy framework and context
The EPBD sets requirements related to the ‘smartness’ of buildings. Specifically, Article 13 addresses technical building systems. Member States must define requirements to optimise energy use in these systems, as mandated in the Directive’s first paragraph.
Starting from paragraph 9, the requirements for the use of BACS are detailed. Particularly relevant due to its timeliness is point (a) of paragraph 9, which states that, from 31 December 2024, where feasible, non-residential buildings with HVAC systems that have an output exceeding 290 kW must be equipped with BACS.
The same category of buildings, but with HVAC systems with an output exceeding 70 kW, must be equipped with BACS, where feasible, by 31 December 2029.
The following paragraph outlines what BACS must be able to do, namely:
(a) continuously monitoring, logging, analysing and allowing for adjusting energy use;
(b) benchmarking the building’s energy efficiency, detecting losses in the efficiency of technical building systems, and informing the person responsible for the facilities or technical building management about opportunities for energy efficiency improvement;
(c) allowing communication with connected technical building systems and other appliances inside the building, and being interoperable with technical building systems across different types of proprietary technologies, devices and manufacturers;
(d) by 29 May 2026 monitoring of indoor environmental quality.
Paragraph 11 sets out requirements, starting from 29 May 2026, for new buildings or buildings undergoing significant refurbishments. These buildings will need to be equipped with systems to monitor energy efficiency, control systems for the optimal generation, distribution, and storage of energy, and, if feasible, the hydronic balance - meaning the optimal distribution of water used for heating and cooling within the building. Additionally, they must be capable of interacting with external systems to optimise energy resources.
The twelfth and final paragraph sets requirements for lighting systems in non-residential buildings: those with HVAC systems exceeding 290 kW must be equipped with automatic lighting controls by 31 December 2027, while those exceeding 70 kW must comply by 31 December 2029.
Moreover, the Directive addresses the smart readiness of buildings. The Smart Readiness Indicator (SRI) was already introduced in the 2018 revision of the Directive. This rating system assesses the capabilities of a building or building unit to adapt its operation to the needs of the occupant and of the grid and to improve its energy efficiency and overall performance. It serves as a tool to raise awareness of the benefits that building automation and electronic monitoring of technical building systems can bring in terms of energy efficiency and indoor environmental quality.
We will not discuss SRIs further here, as they will be covered in detail on our portal in an upcoming Topic of the Month.
European projects
LIFE projects
Smart Square. Start date: 01/10/2022 - End date: 01/10/2025
Smart Square develops a cloud-based platform for assessing building intelligence using the Smart Readiness Indicator, featuring an SRI observatory and virtual training centre for EU-wide implementation.
SRI2MARKET. Start date: 01/11/2022 - End date: 31/10/2025
The SRI2MARKET project introduces the Smart Readiness Indicator in six countries, guiding national regulations and markets while sharing test phase insights to aid other countries' planning.
LIFE22-CET-REPowerEdU. Start date: 01/09/2023 - End date: 31/08/2026
The REPowerEdU project develops 7 training programmes for technicians on intelligent building energy systems, focusing on energy efficiency, renewables, and reducing energy costs and dependence on Russian gas.
For further in-depth information, we suggest:
LIFE projects supporting SRI
Horizon Europe
BuildON. Start date: 01/05/2023 - End date: 01/11/2026
BuildON aims to develop a Smart Transformer Toolbox to enhance energy performance in various building types, supporting digitalisation, decarbonisation, and smart integration of diverse systems and technologies.
SmartWins. Start date: 01/10/2022 - End date: 30/09/2025
The SmartWins project, in collaboration with Kaunas University of Technology, aims to enhance research on next-generation digital twins for a smart, sustainable, and carbon-neutral built environment. Partnering with leading European institutions, it focuses on research capacity building, networking, and training, aiming to establish KTU as a research hub in sustainable building assessment.
SMARTeeSTORY. Start date: 01/05/2023 - End date: 01/05/2027
The SMARTeeSTORY system uses AI to identify user archetypes and preferences for optimised smart building control. It features interoperable, cyber-secure software and advanced hardware. Deployed at TRL 8, it will be tested in historic buildings in Latvia, Spain, and The Netherlands to enhance energy performance and smartness ratings.
SUSTAIN. Start date: 01/10/2022 - End date: 01/04/2026
The SUST(AI)N project aims to enhance 'smart' buildings by introducing precision-sensing AI processing across devices, enabling distributed intelligence and efficient reconfigurable hardware to improve building awareness.
AccesS. Start date: 01/06/2024 - End date: 31/05/2027
The Universal Accessibility Suite (AccesS) aims to enhance accessibility in smart cities and buildings using AI, Building Information Modelling (BIM) and geographic information system (GIS), focusing on barrier-free environments, energy optimisation, sustainable practices, and adaptive operations across diverse European locations.
Horizon 2020
MODERATE. Start date: 01/06/2022 – End date: 31/05/2026
The MODERATE project addresses the lack of interoperability between datasets in the construction sector by creating an open marketplace, connecting stakeholders with data providers, and developing accessible data analytics services for end-users.
CULTURAL-E. Start date: 01/10/2019 – End date: 31/03/2025
CULTURAL-E emphasises smart technologies like cloud-based house management systems, modular HVAC units, and active window systems for natural ventilation and solar control, enhancing energy efficiency and user involvement in building management.
EXCESS. Start date: 01/09/2019 – End date: 01/12/2024
The EXCESS project aims to develop low-cost Positive Energy Buildings (PEBs) with improved materials and smart technologies, focusing on energy efficiency and testing solutions in four EU countries to meet energy targets.
Syn.ikia. Start date: 01/01/2020 - End date: 30/06/2024
Syn.ikia aims to create sustainable plus-energy neighbourhoods with 100% GHG reduction, 90% renewable energy, and 10% cost savings, using innovative designs, community engagement, and smart technologies in four real-life pilot projects.
Conclusion
New technologies play a decisive role in pursuing the objectives of climate neutrality, and this is particularly true in the field of buildings. Among these are the so-called smart technologies, which can interact with each other at different levels and automate a building's energy management processes to ensure greater energy efficiency and comfort. The European Union, through the EPBD, encourages their use and addresses the obstacles that still hinder their wider adoption through cutting-edge projects.
These technologies are part of a larger puzzle that includes many other pieces, such as the integration of renewable energy, sustainable building materials, passive or low-emission heating and cooling techniques, and innovative, industrialised construction methods. Assembling this puzzle is essential to achieving the decarbonisation of the built environment.
