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OVERVIEW| Smart building co-benefits and key performance indicators

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Photo by Stephan Bechert for Unsplash

Introduction

 

As reported in the final report on Smart Readiness Indicators (SRI) a smart building is a building which can sense, interpret, communicate and actively respond to occupants needs and external conditions. A wider implementation of smart technologies is expected to produce energy savings in a cost-effective manner and to improve indoor comfort adjusting the indoor environment conditions. Furthermore, in a future energy system with a large share of distributed renewable energy generation, smart buildings will be the cornerstone for an efficient demand side energy flexibility.

 

The revised EPBD approved by the European Parliament on April 17, 2018 promotes the implementation of building automation and electronic monitoring of technical building systems, supports e-mobility and introduces the SRI, for assessing the technological readiness of the building and the ability to interact with the occupants and the grid. The aim of the SRI is to raise awareness of the benefits of smarter building technologies and functionalities and make these benefits more evident for building users, owners, tenants, and smart service providers.

 

Relying on the nurturing  and consolidation of the Smart Building Innovation Community (SBIC), H2020 SmartBuilt4EU (SB4EU) project has the objective to support the smart building technologies to reach their full potential and to remove those barriers that slow down the improvement of the energy performance of buildings. One of the tasks carried out within the project aims to define the main co-benefits and key performance indicators (KPIs) that will increase the value of the SRI enabling the definition of an effective business case for smart buildings. Once identified a preliminary set of such co-benefits and KPIs through an extensive literature review, a survey among smart building experts has been conducted to collect feedback and validate the selected indicators. The result of this consultation led to the list introduced herein after.

 

KPIs

 

Smart-ready services impact in several ways the building, its users, and the energy grid. The SRI final report defines a set of seven impact categories: energy efficiency, maintenance and fault prediction, comfort, convenience, health and wellbeing, information to occupants and flexibility for the grid and storage. Co-benefits and KPIs analysis has been divided according to these impact categories.   

 

Energy efficiency

 

This category refers to the impacts of the smart-ready technologies on building energy performances, for instance savings resulting from better control of room temperature settings. Selected indicators are:

 

  • Primary energy consumption: it represents the energy before any transformation that is consumed in the supply chains of the used energy carriers.
  • Energy Demand and Consumption: it refers to all the energy supplied to the final user.
  • Degree of Energetic Self- Supply by renewable energy sources (RES): ratio of energy produced on site from RES and the energy consumption, over a defined period.
  • Load Cover Factor: it represents the ratio of the electrical energy demand covered by electricity produced locally.

Maintenance and fault prediction

 

Automated fault detection and diagnosis has the potential to improve operation and maintenance activities of technical building systems. For instance, filter fouling detection in a mechanical ventilation system leads to lower electricity consumption by the fan and allows to better time maintenance interventions. H2020 EEnvest project dealing with the risk reduction for building energy efficiency investments provided two indicators:

 

  • Lower energy performance gap: building operation presents several inefficiencies compared to project conditions that lead to an energy performance gap. This gap can be reduced by monitoring systems.
  • Lower maintenance and replacement costs: smart-ready services reduce maintenance and replacement costs since they permit to prevent or detect faults and failures.

Comfort

 

Occupants’ comfort refers to conscious and unconscious perception of the physical environment, including thermal, acoustic, and visual comfort. Smart services play an important role in adapting the building indoor conditions to occupant’s needs. Main indicators are:

 

  • Predicted Mean Vote (PMV): thermal comfort can be assessed by this index which predicts the mean value of votes assigned on a thermal sensation scale which goes from -3 to +3 by a group of building occupants.
  • Predicted Percentage of Dissatisfied (PPD): associated with the PMV, this index establishes a quantitative prediction of the percentage of thermally dissatisfied occupants..
  • Daylight factor (DF): concerning visual comfort, this indicator describes the ratio of outside over inside light level, expressed in percent. The higher the percentage, the more natural light is available in the indoor space.
  • Sound pressure level: this indicator assesses the indoor acoustic comfort on the basis of the measured or simulated indoor A-weighted sound pressure level within the living environment.

Health and wellbeing

 

Smart-ready services impact on the wellbeing and health of occupants. For instance a smart control aims at better detecting poor indoor air quality compared to traditional controls, guaranteeing a healthier indoor environment.

 

  • CO2 concentration: the CO2 concentration is a commonly used indicator to determine indoor environmental quality (IEQ). The standard EN 16798-2:2019 sets the limits of CO2 concentration for four different IEQ categories.
  • Ventilation rate: connected to the CO2 generation rate, the ventilation rate guarantees that a proper IEQ can be obtained.

Energy flexibility and storage

 

In a grid where the share of intermittent renewable energy sources is growing, smart technologies aim at shifting building energy demand in time to create a better match with energy supply. Thi category does not apply to electrical grids only, but also includes other energy carriers, such as district heating and cooling grids.

 

  • Annual Mismatch Ratio: the annual difference between demand and local renewable energy supply.
  • Load Matching Index: it refers to the match between the load and onsite generation.
  • Grid Interaction Index: describes the average grid stress, using the standard deviation of the grid interaction over a period of a year.

Information to occupants

 

This category refers to the ability of the building and its systems to provide information on building operation and behaviour to occupants or to facility managers. Information such as indoor air quality, production from renewables and storage capacity.

 

  • Consumer engagement: studies showed that frequent feedback to occupants can lead to a household’s final energy consumption reduction in the range from 5% to 10%, supporting change in occupant behavior.

Convenience

 

This category aims at collecting those impacts which “make life easier” for the occupant. It can be defined as the ability to facilitate the user's life, the ease with which the user accesses the services. This category was the most difficult to assess in terms of indicators, due to the lack of literature references on the topic, nevertheless characteristics which better identify co-benefits of smart services in this category are:

 

  • Ability to interact with building services that are always updated, without the user having to deal with it.
  • Features and functionalities that adapt to the user’s changing needs.
  • Ability to access information and controls from a single point or at least with uniformity of approach (user experience).
  • Reporting / summary of monitored data and suggestions to the user.

Conclusion

 

Most relevant co-benefits and KPIs associated with smart buildings have been displayed as a result of literature and projects review activity performed within the H2020 SmartBuilt4EU project. The next steps are a deeper analysis of the most difficult categories in terms of KPIs identification such as convenience where not enough consensus was found, information to occupants and maintenance and fault prediction. The selected KPIs will be coupled with a quantification methodology. The results of these activities together with the literature references will be collected in project deliverable 3.1, foreseen this September. More information can be found on SmartBuilt4EU web portal (www.smartbuilt4eu.eu).