Tallinn University of Technology

One of the pilot projects of the Smart City Challenge 2020 is DigiAudit, which tackles the problems with energy performance and indoor climate of buildings through digitalization and continuous monitoring.


DigiAudit platform will provide scientific tools for breakdown of key performance indicators, visualization of results, diagnostics and information required for planning renovation. Data collection in buildings results in a big data for which developed performance analytics can evaluate energy use and indoor climate, make comparisons with other similar buildings, and identify faults and malfunctions.

Previous studies have shown that actual energy use in buildings can be double the expected level if not monitored and detected issues are not addressed. Without real-time and detailed information about the main energy consumers it tends to be difficult to achieve high performance. Large building portfolio owners often do not have monitoring systems and detailed analysis of the energy use that would be needed for effective management. The energy performance certificates are renewed based on measured data after every 10 years without any significant analysis. Real-time building performance audit will offer automated analyses and dynamic energy performance certificates.

While the energy use of buildings has been in focus for more than 10 years, the indoor climate and ventilation of buildings have also become a relevant topic during the last year due to the coronavirus pandemic. The focus is especially on ventilation systems of educational buildings. Currently, there is a limited overview of indoor climate parameters such as ventilation airflow rates and CO2 levels because of lack of sensors in buildings. Project addresses these issues by installing new sensors for monitoring indoor climate which can store data and allowing analysis of the readings collected. Based on monitoring results, new indoor climate certification framework will be developed, which is similar to the energy performance certificates. Indoor climate certificate is based on algorithm that includes measured parameters and building occupants’ feedback. The indoor climate is characterized by measurable standardized parameters (e.g. room temperature and CO2 level) and occupants perception. Therefore, indoor climate assessment is a combination of measurements and occupant feedback. Research challenge is combining all the indoor climate aspects in to a easily understandable indoor climate certificate.

DigiAudit targets local municipalities and other potential entities with large real estate portfolios. Project partners city of Tallinn and city of Tartu have long-term goals to become a climate-neutral city by 2050. Overview of the energy consumption and indoor climate condition of their buildings helps municipalities to reduce the carbon footprint of buildings while providing good indoor climate quality. Demo buildings reflect the cross-section of the municipal building portfolio: schools, kindergartens, offices and social care buildings. In addition to the municipality buildings, TalTech campus buildings are also included as demo buildings. In total, 45 buildings will be connected to the IoT platform.

Implementation of the real-time building performance audit will result in energy savings and indoor climate improvement and provides benchmarking and technical condition data needed for the decision making and implementation of renovation strategies such as national Long Term Renovation Strategy and Green Deal Renovation Wave. DigiAudit project will end up with dashboards, performance analytics tools and services tested in the cities and university buildings that means a tested prototype of the real-time building performance audit services.

There are four Smart City pilot projects that have been chosen from Smart City Challenge 2020 and in 2021 two more ideas will be chosen. This pilot programme is managed by the Smart City Centre of Excellence and financed by the European Regional Development Fund and the Estonian Ministry of Research and Education.