International Journal of Solar Thermal Vacuum Engineering

Analysis of indoor environment and performance of net-zero energy building with vacuum glazed windows

2021-08-25T15:27:22+00:00

The total energy and indoor thermal environment of an office building, which aims at the net-zero energy building, were measured and analysed. The annual total primary energy consumption of ‘Measurement’ was smaller than the value of ‘Calculation’ at design phase and achieved net-zero. The result of analysis of the thermal environment shows that the comfortable thermal environment was maintained. Also, the insulation performance and heat balance of the vacuum glazed windows in winter was evaluated. The overall heat transfer coefficients calculated by using the monitoring data were almost equal to the rated overall heat transfer coefficient and the high insulation performance of vacuum glazed windows was maintained even in the second year’s operation. In addition, the amount of heat gain due to solar radiation on the window surface was much larger than the amount of heat loss due to transmission. The vacuum glazed windows with high thermal insulation performance on the south side can reduce the heating load and contribute to the achievement of net-zero in the buildings.

Analysis of indoor environment and insulation performance of residential house with double envelope vacuum insulation panels

2021-08-25T15:28:00+00:00

Double envelope vacuum insulation panels (VIPs) have a possibility to significantly increase the service lifetime. In this paper, double envelope VIPs were produced and installed in the residential house. The performance of installed VIPs was evaluated by using the measuring data of heat flux meter. In addition, the total energy, the heating load and the indoor thermal environment of this house were measured and analysed. The average heating load and the average temperature difference between room temperature and ambient air temperature on the representative day was 2.49 kW and 29.9 ^oC, respectively. The heat loss coefficient per floor area was estimated as 0.69 W/(m²K) and it was almost the same as the value calculated at the time of design. The result of indoor environment measurement showed that the room temperature was maintained at around 20 ^oC and PMV was -0.5 ^oC or higher although the outside air temperature fluctuated between -5 ^oC and -10 ^oC. The effective thermal conductivities of double envelop VIPs were all estimated as 0.01 W/(mK) or less. It is considered that the insulation performance of the vacuum insulation panels is maintained.

Predictive permanent magnet synchronous generator based small-scale wind energy system at dynamic wind speed analysis for residential net-zero energy building

2021-08-25T15:28:58+00:00

Integration of small-scale wind energy system to residential buildings for a target to achieve net-zero CO₂ emissions is a revolutionary step to reduce the dependency on the national grid. In this paper, a predictive 20 kVA permanent magnet synchronous generator (PMSG) based small scale wind turbine is investigated at dynamic wind speed with a sensing control system to manage and monitor the power flow for a supply to a typical residential building. A control system is applied that regulates the power from the wind turbine. Results indicate that the proposed control system maximizes the power efficiency within the system. The maximum power generation capacity of the wind turbine is 20 kWh with 415 VAC and 50 Hz frequency. A storage system of 19.2 kWh that supplies the energy to the load side. The applied control unit improves the energy management and protects the power equipment during the faults. The research is conducted using MATLAB/SIMULINK and mathematical formulations.

Daylighting, artificial electric lighting, solar heat gain, and space-heating energy performance analyses of electrochromic argon gas-filled smart windows retrofitted to the building

2021-08-25T15:29:40+00:00

The inevitability to reduce CO₂ emissions to avoid preventable climate change is widely being yelped. To minimise the impact of rapidly changing climate, this paper presents novel research findings and contributes to developing electrochromic argon gas-filled glazed smart windows retrofitted to the building with IoT based transparency control. In this, the comparative analyses of the daylighting, electrical lighting, solar heat gain, and space-heating load of the building using the dynamic thermal and electric lighting modelling methods based on real weather temperatures are presented. The daylighting analysis results implicate that the building with electrochromic argon gas-filled smart windows reduced 19% of daylight illuminance during summer months compared with the building retrofitted with double air-filled glazed windows daylight factor remains consistent. As such, the solar heat gains analysis results implicate at least 50 % annual solar heat gain reduction predicted in the building with electrochromic argon gas-filled smart windows in comparison to double air-filled windows. This leads to the conclusion of the space-heating energy analysis that implicates the highest contribution to the space heating demand is the solar heat gain caused by double air-filled glazed windows. The results confirm that the LED artificial electric lighting system requires fewer fittings and thus total power load compared to the fluorescent lighting system, throughout the year, to the building with electrochromic argon gas-filled glazed smart windows. The daylight controls are linked to the electrochromic argon gas-filled glazed smart windows, so they only operate when the glazing is tinted, or the daylight level drops below a set level; this will reduce the energy usage and also lower the space heating of the room.

Enhancing the renewable energy payback period of a photovoltaic power generation system by water flow cooling

2021-08-25T15:30:19+00:00

A photovoltaic system which enjoys water flow cooling to enhance the performance is considered, and the impact of water flow rate variation on energy payback period is investigated. The investigation is done by developing a mathematical model to describe the heat transfer and fluid flow. A poly crytalline PV module with the nomical capacity of 150 W that is located in city Tehran, Iran, is chosen as the case study. The results show that by incresing water flow rate, EPBP declines first linearly, from the inlet water flow rate of 0 to 0.015 kg.s^-1, and then, EPBP approaches a constant value. When there is no water flow cooling, EPBP is 8.88, while by applying the water flow rate of 0.015 kg.s^-1, EPBP reaches 6.26 years. However, only 0.28 further years decreament in EPBP is observed when the inlet water mass flow rate becomes 0.015 kg.s^-1. Consequently, an optimum limit for the inlet water mass flow rate could be defined, which is the point the linear trend turns into approaching a constant value. For this case, as indicated, this value is 0.015 kg.s^-1.