Abstract
Achieving nearly zero-energy buildings (nZEB) is one of the main objectives defined by the European Union for achieving carbon neutrality in buildings. nZEBs are heavily reliant on distributed renewable generation energy sources, which create new challenges associated with their inherent intermittency. To achieve nZEB levels, demand management plays an essential role to balance supply and demand. Since up to two-thirds of the total consumed energy in buildings is dispended for Heating, Ventilation and Air Conditioning (HVAC) operations, intelligent control of HVAC loads is of utmost importance. The present work aims to offer a solution to improve a building microgrids’ flexibility by shifting thermal loads and taking advantage of room thermal inertia. Innovation is present in using the internet of things to link several decentralized local microcontrollers with the microgrid and in the applicability of different control algorithms, such as the pre-emptive heating/cooling of a room. The developed solution relies on smart thermostats, which can be integrated into a building management system, or in a microgrid, and are capable of fulfilling the occupants’ need for comfort while complementing the building with needed power flexibility. The equipment is capable of controlling several HVAC systems to guarantee thermal and air quality comfort, as well as coordinate with a building/microgrid operator to reduce energy costs by shifting thermal loads and enacting demand control strategies. The smart thermostat uses an algorithm to calculate room inertia and to pre-emptively heat/cool a room to the desired temperature, avoiding peak hours, taking advantage of variable tariffs for electricity, or periods of solar generation surplus. The smart thermostat was integrated into a university campus microgrid and tested in live classrooms. Since the work was developed during the COVID-19 pandemic, special attention was given to the air quality features. Results show that smart HVAC control is a viable way to provide occupant comfort, as well as contribute to the integration of renewable generation and increase energy efficiency in buildings and microgrids.
Highlights
The method achieves a reduction in 37% of energy consumption by avoiding the On/Off type cycle typical of most HVAC systems
Using a mathematical model of the room, the smart thermostat calculates the starting time required to have the room heated to the desired temperature at a avoid peak hour operation was tested and compared with the most common utilization in heating equipment
Energy efficiency tests showed that the smart thermostat successfully managed to pre-heat a room
Summary
The world is facing new challenges resulting from increased energy demand, resource high costs/scarcity and the urgent need to combat climate change. Worldwide efforts are being made to increase the penetration of renewable energy sources and improve energy efficiency. Energy efficiency is a valuable tool to address these challenges and to manage energy demand: It reduces primary energy consumption, reduces costs and resources and reduces greenhouse gas emissions. In the European Union, buildings account for 40% of the total energy consumption and 36% of the greenhouse gas emissions [1]. To promote energy efficiency in buildings, the EU has established several directives [2,3] that cover measures and policies to boost EU energy performance such as promoting building renovation, issuing energy certificates and making it obligatory for all new buildings built after 2020 to be near zero-energy buildings (nZEB) [4]
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