# Performance of a Mid-Size Net-Zero Energy Solar House
## 2 Previous Research Studies on Net-Zero Energy Buildings  
Several research studies have been conducted addressing the feasibility of net-zero energy buildings. These studies are briefly described below. [PERSON] and [PERSON] [8] conducted detailed analyses for net-zero energy buildings in Estonia. By the end of 2018, all new public buildings and all new buildings by the end of 2020 are required to be nearly zero energy buildings (NZEB). NZEB are defined as buildings with a very good energy performance along with having nearly zero (or a very low amount of) energy need covered by energy from nonrenewable resources. A NZEB typically involves an energy grid-connected building with a very high energy performance. It uses on-site produced electricity under suitable conditions and uses delivered energy the rest of the time. Well-insulated buildings, effective building service systems, and local electricity production are needed for NZEBs. Research questions addressed in the study of [PERSON] and [PERSON] [8] were: Is it theoretically possible to achieve a NZEB without on-site electricity production using photovoltaic (PV) panels, and is it possible to achieve a NZEB level if PV panels with a nominal power of 100 kW are installed? They addressed the building energy performance expressed as annual primary energy usage and presented as an energy performance value expressed in kWh/m\({}^{2}\) per year The authors looked at the building's total weighted specific energy use for detached houses, multi-apartment buildings, office buildings, public buildings, schools and other educational buildings, and kindergarten and day care centers. The energy calculations considered the heating systems involving energy use for space heating, heating of ventilation air, and heating of domestic hot water. Simulations were performed to estimate the indoor comfort and energy use of the building. Their results indicated it is possible to achieve NZEB levels in buildings in Estonia through careful design of the building's energy performance. [PERSON] [9] performed a comparative analysis of simulated and monitored energy performance of a prototype house in Dubai, United Arab Emirates (UAE). The UAE Vision 2021 addresses environmental sustainability aimed at reducing greenhouse gas emissions. The author noted that the building sector is among the largest energy consumers globally, accounting for nearly 40% of the overall share in western countries and nearly 70% in the UAE. The research investigation's objective was to assess the energy calculation assumptions and validate the suitability of the prediction of the design simulation. The simulations were performed using the DesignBuilder/EnergyPlus 8.0 software. The monitored results were validated by a third-party organization. [PERSON]'s study considered architectural design of the project, geometric features and orientation, construction design for energy efficiency, different shading devices and their location, HVAC systems, and passive design to enhance natural ventilation and cooling. The study demonstrated the efficiency and utility of using energy simulations for developing NZEBs. A design concept developed by [PERSON] et al. [10] was investigated, reporting the monitoring results for a Solar Decathlon house that participated in the Solar Decathlon Europe 2019 competition. Their house was designed as a lightweight rooftop house that can be placed on top of a new row house in Bangkok, Thailand. The additional rooftop house increases the living space on an existing building, plus it ensures the existing building is more viable, comfortable, and eco-friendly. Their house was monitored for its energy performance during the 10 days of the Solar Decathlon competition (15 July through 25 July 2019). Analysis of those results indicated the house was net positive with 171.81 kWh which was the highest value of all the competitors. The energy consumption was only 37.65 kWh.