Calibration of Predicted Hourly Zone-Level Supply Air Flows with Measurements

The calibrated building energy models can be used for the verification and improvement of building operation. This paper proposes a bottom-up approach for the assisted calibration of a building energy model developed with eQuest program, and using data extracted from the Building Energy Management System (EMS). The paper presents the calibration of predicted hourly zone-level supply air flows with measurements. The suggested approach is applied to a new institutional building of Concordia University. The paper presents results from different techniques to assess the agreement quality

Annual Performance Of A Solar Assisted Heat Pump Using Ice Slurry As A Latent Storage Material

Solar assisted heat pump systems offer an attractive method of reducing the energy used for space heating and cooling, while efficiently using low temperature renewable energy from the sun to reduce the degradation of heat pump performance at low ambient temperatures. However, the majority of these systems use sensible storage to bridge the gap between thermal supply and demand, with the maximum storage capacity limited by physical constraints within the building. Latent storage has the potential to significantly reduce the required tank volumes in these types of systems. Previous work has demonstrated the benefit in heating mode of combining a solar heat pump system with ice based latent thermal storage, with this type of system achieving an up to 86% reduction in space heating energy use compared to a conventional system. The objective of this paper is to expand upon these findings and examine annual system performance in various Canadian climate regions through the evaluation of an innovative new operational mode providing space cooling to the building. The proposed system has distinct heating and cooling modes of operation. In heating mode, energy obtained from the solar collectors is stored in the ice tank. Thermal energy is then extracted from the ice tank using a heat pump, and delivered to a warm water tank acting as the distribution point for heating and DHW loops. An innovative new cooling mode is also presented, where the heat pump is used to build a cold storage reservoir for cooling purposes during the summer months. Excess thermal energy is then dissipated at night using radiative cooling (via solar collectors) or an air cooled condenser. Anticipated system benefits include increased energy storage densities, improved solar collector efficiencies, and potential utility cost savings by operating the heat pump during off-peak hours. To perform the analysis a computer model of the proposed system is developed using the TRNSYS energy simulation program, and integrated into high performance homes in three Canadian regions (Montreal, Toronto, Vancouver). Annual simulation results are presented and compared with typical base case designs in order to assess the viability and potential energy savings. A sensitivity analysis on several system variables is then presented in order to identify key design parameters for improved energy performance

The Potential of Liquid-Based BIPV/T Systems and Ice Storage for High Performance Housing in Canada

ASHRAE Vision 2020 has defined market viable net-zero energy buildings as a key objective for new construction in North America. Designing for this target requires the effective integration of renewable energy systems into the building. However, many buildings have limited roof and façade areas in which to integrate these systems, making it difficult to achieve a net zero energy design. Building Integrated Photovoltaic and Thermal (BIPV/T) offers a potential solution to this issue by converting the building envelope into an active producer of both thermal and electrical energy. Commonly, BIPV/T systems in North America have used air as a working fluid. While this offers easy integration with the building ventilation system, air also has a lower thermal capacitance, reducing thermal energy extracted from a BIPV/T collector. Liquid based systems offer working fluids with higher thermal capacitance, along with the ability to easily integrate with existing thermal storage systems. However, these systems often circulate warm water in order to directly meet heating and hot water loads, resulting in reduced thermal and electrical efficiencies and less durable BIPV/T modules. Circulating cooler water to the collectors can significantly improve both the thermal and electrical efficiencies of liquid based BIPV/T systems. However, the low grade thermal energy collected must then be upgraded for use within the building. This paper examines the potential of using liquid based BIPV/T systems with cool storage and heat pump technologies to meet the thermal demands of a high performance Canadian home. An innovative liquid based BIPV/T system is proposed in which the collector array is connected to a cool storage tank, while a heat pump is used to upgrade and deliver thermal energy to the building. Both sensible and ice-based latent storage options are examined as cool storage possibilities. To perform the analysis, TRNSYS is used to simulate the proposed system integrated into a high performance home in Montreal, Canada. Annual simulation results are presented and compared with typical base case designs. A more detailed temporal analysis of electrical loads is also performed in order to examine the impact of the proposed system on the electricity grid.

Internal heat gain from different light sources in the building lighting systems

EU directives and the Construction Law have for some time required investors to report the energy consumption of buildings, and this has indeed caused low energy consumption buildings to proliferate. Of particular interest, internal heat gains from installed lighting affect the final energy consumption for heating of both public and residential buildings. This article presents the results of analyses of the electricity consumption and the luminous flux and the heat flux emitted by different types of light sources used in buildings. Incandescent light, halogen, compact fluorescent bulbs, and LED bulbs from various manufacturers were individually placed in a closed and isolated chamber, and the parameters for their functioning under identical conditions were recorded. The heat flux emitted by 1 W nominal power of each light source was determined. Based on the study results, the empirical coefficients of heat emission and energy efficiency ratios for different types of lighting sources (dependent lamp power and the light output) were designated. In the heat balance of the building, the designated rates allow for precise determination of the internal heat gains coming from lighting systems using various light sources and also enable optimization of lighting systems of buildings that are used in different ways

Multi-objective optimal design of a near net zero energy solar house

This paper presents a multi-objective redesign case study of an archetype solar house based on a near net zero energy (NZE) demonstration home located in Eastman, Quebec. Using optimization techniques, pathways are identified from the original design to both cost and energy optimal designs. An evolutionary algorithm is used to optimize trade-offs between passive solar gains and active solar generation, using two objective functions: net-energy consumption and life-cycle cost over a thirty-year life cycle. In addition, this paper explores different pathways to net zero energy based on economic incentives, such as feed-in tariffs for on-site electricity production from renewables. The main objective is to identify pathways to net zero energy that will facilitate the future systematic design of similar homes based on the concept of the archetype that combines passive solar design; energy-efficiency measures, including a geothermal heat pump; and a building-integrated photovoltaic system. Results from this paper can be utilized as follows: (1) systematic design improvements and applications of lessons learned from a proven NZE home design concept, (2) use of a methodology to understand pathways to cost and energy optimal building designs, and (3) to aid in policy development on economic incentives that can positively influence optimized home design

Use of Building Automation System Trend Data for Inputs Generation in Bottom-Up Simulation Calibration

Ongoing commissioning based on calibrated energy models is one of the most promising means to improve the energy performance of existing buildings. The bottom-up calibration approach starts the calibration on a zone level before sequentially calibrating the system, plant, and whole-building level models. The hypothesis is that bottom-up calibration can create more reliable and accurate models than those created with existing approaches. The number of candidate measurement points to be considered for analysis and use in simulation is very large. This paper explores automating the process of generating inputs from Building Automation System (BAS) trend data for use in building simulation software. A proof-of-concept prototype called the Automatic Assisted Calibration System (AACS) was created which generated multiple eQUEST inputs from BAS trend data obtained from a case study building

An information driven hybrid evolutionary algorithm for optimal design of a Net Zero Energy House

Building Performance Simulation (BPS) is a powerful tool to estimate and reduce building energy consumption at the design stage. However, the true potential of BPS remains unrealized if trial and error simulation methods are practiced to identify combinations of parameters to reduce energy use of design alternatives. Optimization algorithms coupled with BPS is a process-orientated tool which identifies optimal building configurations using conflicting performance indicators. However, the application of optimization approaches to building design is not common practice due to time and computation requirements. This paper proposes a hybrid evolutionary algorithm which uses information gained during previous simulations to expedite and improve algorithm convergence using targeted deterministic searches. This technique is applied to a net-zero energy home case study to optimize trade-offs in passive solar gains and active solar generation using a cost constraint

Parametric study of air curtain door aerodynamics performance based on experiments and numerical simulations

Air curtains have been widely used to reduce infiltration through door openings and save heating/cooling energy in different types of buildings. Previous studies have found that there exist three aerodynamics conditions: optimum condition (OC), inflow break-through (IB), and outflow break-through (OB) conditions, which are important for categorizing air curtain performance subject to such key parameters including supply speed and angle, and presence of a person during an actual operation. However, few studies have focused on the effects of these parameters on air curtain performance in terms of resisting infiltration and reducing exfiltration. This research presents a parametric study of air curtain performance based on reduced-scale experiments and full-scale numerical simulations. It was found that increasing air curtain supply angle improves air curtain performance when it is operated under the OC and IB conditions but creates excessive exfiltration under the OB condition. Increasing supply speed of air curtain generally improves the air curtain performance whereas this improvement deteriorates with the increase of supply angle under the OB condition. The presence of person, either directly under or below the air curtain, almost has no effect on the infiltration/exfiltration during the OC condition. Moreover, the person in the doorway can block airflow from both directions, contributing to less infiltration under the IB condition and less exfiltration under the OB condition than without the person. This study provides valuable insights into air curtain aerodynamics performance under different operational conditions and key contributing parameters

Thermodynamic analysis of humidification dehumidification desalination cycles

Humidification–dehumidification desalination (HDH) is a promising technology for small-scale water production applications. There are several embodiments of this technology which have been investigated by researchers around the world. However, from a previous literature [1], we have found that no study carried out a detailed thermodynamic analysis in order to improve and/ or optimize the system performance. In this paper, we analyze the thermodynamic performance of various HDH cycles by way of a theoretical cycle analysis. In addition, we propose novel high performance variations on those cycles. These high-performance cycles include multi-extraction, multi-pressure and thermal vapor compression cycles. It is predicted that the systems based on these novel cycles will have gained output ratio in excess of 5 and will outperform existing HDH systems.King Fahd University of Petroleum and MineralsCenter for Clean Water and Clean Energy at MIT and KFUP

Exergy performance of different space heating systems: A theoretical study

Three space heating systems (floor heating with different floor covering resistances, radiator heating with different working temperatures, warm-air heating with and without heat recovery) were compared using a natural gas fired condensing boiler as the heat source. For the floor heating systems, the effects offloor covering resistance on the whole system performance were studied using two heat sources; a natural gas fired condensing boiler and an air-source heat pump. The heating systems were also compared in terms of auxiliary exergy use for pumps and fans.The low temperature floor heating system performed better than other systems in terms of exergy demand. The use of boiler as a heat source for a low-exergy floor heating system creates a mismatch in the exergy supply and demand. Although an air-source heat pump could be a better heat source, this depends on the origin of the electricity supplied to the heat pump. The coefficient of performance (COP) of the heat pump has a critical value (2.57 in this study); it is beneficial to use a heat pump instead of a boiler only when the COP is above this critical value.The floor covering resistance should be kept to a minimum, in order not to hinder the performance of the floor heating and the whole system. The exergy input to auxiliary components plays a significant role in the overall exergy performance of systems, and its effects become even more significant for low temperature heating systems