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Climate has the most profound impact on the buildings' energy performance, especially now due to the ongoing global weather changes. Therefore, selecting appropriate weather data for building energy simulation is crucial. This paper aims to advance the knowledge about the use of different weather datasets for building performance simulation by addressing the following research objectives: (i) understanding the statistical relevance of using a typical weather year (TWY) for running building energy simulations, if compared to a series of actual weather years (AWY), for different buildings' typologies and under different climate conditions; (ii) verifying the role of building features on the discrepancies between TWY-based and AWY-based simulations. Tackling these objectives implied simulating a complex university building and a typical single-family dwelling by using two TWYs and ten AWYs pertaining to data recorded from 2010 to 2019 in both cold (i.e., Winnipeg, Canada) and warm (i.e., Catania, Italy) climates. Results show that in Winnipeg, TWYs predicted from 2.7% to 11.3% lower heating demand and from 10.5% to 82.4% higher cooling demand than the average long-term from AWYs, while in Catania TWYs predicted from 1.8% to 8.7% lower cooling demand and from 2.8% to 82.4% higher heating demand, suggesting that buildings designed using TWYs might not perform as modelled under actual weather conditions. • Evaluation of different TWYs and AWYs on the dynamic energy simulation of buildings. • TWYs and AWYs are developed from recent (2010–2019) weather observations. • Buildings with different features and under different climates are analysed. • TWYs could understimate the dominant energy demand in the range of 2%–11%. • TWYs could overestimate the minor energy demand in the range of 3%–83%. [ABSTRACT FROM AUTHOR]

Phase change material (PCM)-enhanced building envelopes can control indoor temperatures and save energy. However, PCM needs to undergo a phase change transition from solid to liquid and back to be fully effective. Furthermore, most previous research integrated PCM with high embodied energy materials. This study aims to advance the existing research on integrating PCM into carbon-negative wall assemblies composed of hempcrete and applying temperature control strategies to improve wall systems' performance while considering the hysteresis phenomenon. Four hempcrete and hempcrete-PCM (HPCM) wall design configurations were simulated and compared under different control strategies designed to reduce energy demand while enhancing the phase change transition of the microencapsulated PCM. The HPCM wall types outperformed the hempcrete wall assembly through heating (~3–7%) and cooling (~7.8–20.7%) energy savings. HPCM walls also maintained higher wall surface temperatures during the coldest days, lower during the warmest days, and within a tighter range than hempcrete assembly, thus improving the thermal comfort. However, the results also show that the optimal performance of thermal energy storage materials requires temperature controls that facilitate their charge and discharge. Hence, applied control strategies reduced heating and cooling energy demand in the range of ~4.4–21.5% and ~14.5–55%, respectively. [ABSTRACT FROM AUTHOR]

A deep energy retrofit of building envelopes is a vital strategy to reduce final energy use in existing buildings towards their net-zero emissions performance. Building energy modeling is a reliable technique that provides a pathway to analyze and optimize various energy-efficient building envelope measures. However, conventional optimization analyses are time-consuming and computationally expensive, especially for complex buildings and many optimization parameters. Therefore, this paper proposed a novel optimization algorithm, MEVO (metamodel-based evolutionary optimizer), developed to efficiently identify optimal retrofit solutions for building envelopes while minimizing the need for extensive simulations. The key innovation of MEVO lies in its integration of evolutionary techniques with design-of-computer experiments, machine learning, and metaheuristic optimization. This approach continuously refined a machine learning model through metaheuristic optimization, crossover, and mutation operations. Comparative assessments were conducted against four alternative metaheuristic algorithms and Bayesian optimization, demonstrating MEVO's effectiveness in reliably finding the best solution within a reduced computation time. A hypothesis test revealed that the proposed algorithm is significantly better than Bayesian optimization in finding the best cost values. Regarding computation time, the proposed algorithm is 4–7 times faster than the particle swarm optimization algorithm and has a similar computational speed as Bayesian Optimization. [ABSTRACT FROM AUTHOR]

Solar energy is one of the most promising forms of alternative energy because it has no adverse effects on the environment and is entirely free. Converting solar energy into thermal energy is the most common and straightforward method; the efficiency of solar thermal conversion is approximately 70 percent. The intermittent nature of solar energy availability affects the performance of solar water heaters (SWH), which lowers the usefulness of solar energy in residential and commercial settings, particularly for water heating. Even at low temperatures, the performance of a collector can be improved by using low-density polyethylene (LDPE) glazing instead of traditional glass because it is less expensive and lighter than glass. Using a comprehensive experimental-simulative study, the Glass Solar water heater (glass SWH) and the low-density polyethylene solar water heater (LDPE SWH) are analyzed, examined, and compared in this work. These solar water heaters have galvanized iron (GI) as their absorber material. The SWHs were operated in a closed loop at a constant mass flow rate of 0.013 kg/s, and a 4E analysis (which stands for energy, exergy, economics, and efficiency recovery ratio) was carried out. This analysis included a look at the dynamic time, uncertainty, weight reduction, carbon footprint, and series connection. An LDPE SWH has an energy efficiency that is 5.57% and an exergy efficiency that is 3.2% higher than a glass SWH. The weight of the LDPE SWH is 32.56% lower than that of the glass SWH. Compared to the price of a conventional geyser, installing our SWH results in a cost savings of 40.9%, and monthly energy costs are reduced by an average of 25.5%. Compared to October, September has the quickest dynamic time to reach the desired temperature, while October has the most significant dynamic time. The efficiency recovery ratio (ERR) of a glass SWH is 0.0239% lower than that of an LDPE SWH. LDPE SWHs had a carbon credit worth INR 294.44 more than glass SWHs. The findings of these tests demonstrate that the LDPE SWH is a practical replacement for traditional means of heating water, such as SWHs and geysers. [ABSTRACT FROM AUTHOR]

A model predictive control strategy method is developed for a LEED silver community college building that contains an advanced common loop heat pump HVAC system. MPC is performed using persistence based climate forecasting with two scenarios examined: fixed temperature setpoint pairs; and a deadband of 1 °C between the heating/cooling setpoint. EnergyPlus acts as the “real” building and is linked with R software for model predictive control via the Building Controls Virtual Test Bed. A statistical based building response model is created in R using training data from a calibrated EnergyPlus model. A brute force optimization strategy is used for solving the objective function. A piece-wise objective function maintains thermal comfort during occupied periods with a focus on reducing energy consumption during other periods. Results when using fixed setpoint pairs exhibit a 4% reduction in HVAC energy consumption, and deadband setpoints exhibit a 9% reduction in HVAC energy consumption, compared with reactive rule based control. Of interest is that the type of energy savings (thermal energy vs electricity) varies depending upon the setpoint options. The results are promising given the strict thermal comfort requirement employed, minimal search space, use of simplistic persistence forecasting, and the sophisticated HVAC system. [ABSTRACT FROM AUTHOR]

• @ Source -Energy pipe deemed sustainable for 25 year period. • Horizontal spacing of system should occur at 8 m for large scale applications. • @ Source -Energy pipe deemed sustainable for 4, 5, 6, 7, and 8 m depths. • HDPE shows negligible effects on thermal performance of system. • @ Source -Energy pipe deemed sustainable for 50 % and 75 % sewage pipe capacity. Extracting heat from a sewage pipe through a typical horizontal ground heat exchanger has recently been introduced as a renewable energy alternative to reduce fossil fuel usage. This paper presents a novel design for a ground heat exchanger that extracts heat from the surrounding soil and sewage within the pipe while simultaneously being carried to a wastewater treatment plant. This research focuses on the long-term efficiency of the system under transient conditions in a cold climate. A numerical model using COMSOL Multiphysics was developed to verify the sustainability of the system for over 25 years. The model used constant inlet fluid temperatures to evaluate heat transfer with convective pipe flow and conductive phase change within the soil. The results showed a maximum temperature change in the surrounding soil adjacent to the heat extraction system over 25 years was 0.10 °C during the heating season in Winnipeg, Manitoba. The distance at which the heat extraction system did not show an impact on temperature change of adjacent soil was determined at 4 m. Critical parameters in this evaluation were system depth, sewage level, and the high-density polyethylene pipe thermal properties. The sustainability of the system was not affected by the system depth due to thermal balancing between climatic, subsurface and sewage heat fluxes. Sustainable behavior was achieved at 50 % and 75 % of sewage pipe capacity. The effect on thermal performance from the high-density polyethylene pipe thermal properties was deemed insignificant. [ABSTRACT FROM AUTHOR]

Natural gas and electricity together accounted for 82.5% of all residential energy use in Canada in 2013 with nearly half of the average household consumption from natural gas used for heating. Energy demand is projected to grow exponentially due to population increase. In May 2015, Canada submitted its Intended Nationally Determined Contribution to the United Nations Framework Convention on Climate Change which included an economy-wide target to reduce greenhouse gas emissions by 30% below 2005 levels by 2030. As of 2016, Canada is projected to significantly miss its 2020 and 2030 climate target with the set of measures it currently has in place. The projected target for 2020 is 622 mega tons of carbon dioxide equivalent (Mt CO2 eq.) and the projected outcome is 768 Mt CO2 eq. The projected target for 2030 is 524 Mt CO2 eq. and the projected outcome is 815 Mt CO2 eq. This leads to the demand of innovative solutions to reduce fossil fuel usage and to switch to renewable energy. A recent heat extraction system has been developed that combines a typical horizontal ground heat exchanger with a sewage pipe. The heat extraction system is a hollow concrete cylinder with a helical high-density polyethylene pipe embedded within the pipe walls. The high-density polyethylene pipe has an outlet and inlet on each length of pipe which are attached to a heat pump which circulate a heat exchange fluid. As the heat exchange fluid cycles through the system, it extracts heat from the surrounding soil and sewage within the pipe while simultaneously carrying the sewage to a waste treatment plant. A heat pump uses the obtained energy to heat a building in cold weather and cool a building in hot weather. This system has not been studied under transient conditions in an extreme climate. In this study, a numerical model is developed using the finite element solver COMSOL Multiphysics to investigate heat transfer coupled with fluid flow by solving partial differential equations where temperature is the dependent variable. A soil block is initially modelled to simulate a control scenario of ground temperature in order to extract data at specific locations for specific times. Following are multiple simulations which implemented the heat extraction system with various energy demands into the soil block to compare ground temperatures at specific locations. A five year period of sustainability is demonstrated through comparison of temperature differentials of adjacent soil locations to the benchmarks established. The maximum temperature change over the five year period interpreted is 1.8 degrees centigrade at 0.1 meters adjacent to the heat extraction system for 75% energy demand of a bed and breakfast located south of Winnipeg. The system is shown to handle an energy demand of up to 6 typical residential houses in Winnipeg when the sewage temperature is kept constant. [ABSTRACT FROM AUTHOR]

Abstract Snow melting systems using geothermal energy piles are a clean technology to overcome the problems of traditional chemical-based snow melting methods. This paper aims to study the feasibility of such systems in six major cities (Calgary, Edmonton, Montreal, Ottawa, Toronto and Winnipeg) in Canada. The amount of energy, as well as the inlet temperature of a hydronic system required to warm up and keep the surface temperature of a bridge slab unit above 0 °C during a typical snowfall were determined based on a transient energy balance at the slab surface and weather conditions for each city. The coefficient of performance (COP) of the heat pump for a bridge was then derived for each city based on its specific local geological conditions and heating demands. Also, the problems related to the ground thermal imbalance due to the operation of such systems were addressed. Finally, the economic feasibility study was performed to compare costs between a snow melting system for a bridge deck using geothermal energy piles and an electricity-based heating system. It was concluded that the snow melting system using geothermal energy piles is efficient and cost effective. However, the extent of efficiency and saving varies with implementation areas. Highlights • The COP of the heat pump depends on weather conditions. • Thermal recharging shortly after snowfalls is important. • Winnipeg is the most suitable place for the geothermal pile based heating system. • Snow melting system using geothermal piles is cost effective. [ABSTRACT FROM AUTHOR]

The paper provides a methodology for the optimal control of heating, ventilation, and air conditioning (HVAC) systems used in public buildings, with the purpose of obtaining high comfort and safety standards along with energy efficiency. The combination of the two concurrent objectives of minimizing energy use and guaranteeing high standards of occupant comfort is obtained by means of multi-objective optimization, in which a comfort model is combined along with a dynamic energy model of the building. The use of dynamic setpoints for the HVAC and the inclusion of comfort indicators represent a step forward, compared to the current design and operation procedures suggested by technical standards. The utilization of the proposed methodology is tested with reference to a case study, represented by an academic building used by the University of Pisa for educational purposes, whose extensive and variable occupancy can help to emphasize the importance of comfort in the operation of HVAC systems in different climatic conditions and with different occupancy profiles. We show how this optimization brings interesting results in terms of energy-saving (up to 30%), obtaining an increased comfort level (of more than 25%) compared to the operating conditions suggested by technical standards. [ABSTRACT FROM AUTHOR]

A model predictive control (MPC) system with an adaptive building model based on thermal-electrical analogy for the hybrid air conditioning system using the radiant floor and all-air system for heating is proposed in this paper to solve the heating supply control difficulties of the railway station on Tibetan Plateau. The MPC controller applies an off-line method of updating the building model to improve the accuracy of predicting indoor conditions. The control performance of the adaptive MPC is compared with the proportional-integral-derivative (PID) control, as well as an MPC without adaptive model through simulation constructed based on a TRNSYS-MATLAB co-simulation testbed. The results show that the implementation of the adaptive MPC can improve indoor thermal comfort and reduce 22.2% energy consumption compared to the PID control. Compared to the MPC without adaptive model, the adaptive MPC achieves fewer violations of constraints and reduces energy consumption by 11.5% through periodic model updating. This study focuses on the design of a control system to maintain indoor thermal comfort and improve system efficiency. The proposed method could also be applied in other public buildings. [ABSTRACT FROM AUTHOR]

Hempcrete is a sustainable biocomposite that can reduce buildings' embodied energy while improving energy performance and indoor environmental quality. This research aims to develop novel insulating hemp-lime composites using innovative binder mixes made of recycled and low-embodied energy pozzolans. The characterization of composites' mechanical and hygrothermal properties includes measuring compressive strength, splitting tensile strength, thermal conductivity, specific heat capacity, and moisture buffer capacities. This study also investigates the impact of sample densities and water content on compressive strength at different ages. The findings suggest that mixes with a 1:1 binder to hemp ratio and 300−400 kg/m3 density have hygrothermal and mechanical properties suitable for insulating infill wall applications. Hence, compressive strengths, thermal conductivity, and specific heat capacity values range from 0.09 to 0.57 MPa, 0.087 to 0.10 W/m K, and 1250 to 1557 J/kg K, respectively. The average moisture buffer value for all hempcrete samples of 2.78 (gm/m2 RH%) indicates excellent moisture buffering capacity. Recycled crushed brick pozzolan can enhance the hygrothermal performance of the hemp-lime composites. Thus, samples with 10% crushed brick have the lowest thermal conductivity considering their density and the highest moisture buffer capacity. The new formulas of hydrated lime and crushed brick have mechanical properties comparable to metakaolin and hydraulic lime formulas. [ABSTRACT FROM AUTHOR]