Office Building In Shanghai Research Articles

Optimum control strategy for all-variable speed chiller plant

The optimum control strategy and the saving potential of all variable chiller plant under the conditions of changing building cooling load and cooling water supply temperature were investigated. Based on a simulation model of water source chiller plant established in dynamic transient simulation program (TRNSYS), the four-variable quadratic orthogonal regression experiments were carried out by taking cooling load, cooling water supply temperature, cooling water flow rate and chilled water flow rate as variables, and the fitting formulas expressing the relationships between the total energy consumption of chiller plant with the four selected parameters was obtained. With the SAS statistical software and MATHEMATICA mathematical software, the optimal chilled water flow rate and cooling water flow rate which result in the minimum total energy consumption were determined under continuously varying cooling load and cooling water supply temperature. With regard to a chiller plant serving an office building in Shanghai, the total energy consumptions under different control strategies were computed in terms of the forecasting function of cooling load and water source temperature. The results show that applying the optimal control strategy to the chiller plant can bring a saving of 23.27% in power compared with the corresponding conventional variable speed plant, indicating that the optimal control strategy can improve the energy efficiency of chiller plant.

Evaluation of four control strategies for building VAV air-conditioning systems

It is necessary to adopt appropriate control strategies to save energy and improve the indoor air quality (IAQ). On the validated TRNSYS simulation platform, four different control strategies are investigated to examine the indoor air temperature, energy consumption, CO 2 concentration and predicted mean vote (PMV) for the variable air volume (VAV) systems in an office building in Shanghai. As an original scheme, Strategy A using constant outdoor air intake fraction shows high energy consumption, low CO 2 concentration and acceptable thermal comfort. By using minimum outdoor air ventilation based on dynamic occupancy detection, Strategy B can provide more than 15% energy saving, acceptable PMV value but high CO 2 concentration in breathing zone. By using indoor air temperature reset, Strategy C presents the most energy savings beyond 20% reduction, low CO 2 concentration but poor thermal comfort. In mild seasons, combining enthalpy-based outdoor airflow economizer cycle with supply air temperature reset, Strategy D can achieve 9.4% energy savings and the lowest CO 2 concentration. Taken together, each strategy covers some strengths as well as some weaknesses. How to comprehensively assess a control strategy for all specific objectives should be considered in future studies.

The Analysis and Simulation on Operating Characteristics of GSHP in Summer

At present, being environmental friendly and with the potential of energy efficiency, ground-source heat pump (GSHP) systems are widely used in the world. The GSHP system can transfer heat stored in the earth into a building during the winter, and transfer heat gained in the building into the earth during the summer. An office building in Shanghai which uses a GSHP system and dual-U-pipe vertical geothermal heat exchangers (GHEs) under the ground is taken as an example in this paper for analysis. Experiments on the operation performance of this GSHP system were carried out. When cooling in summer, the soil temperature increased during the day and decreased at night, and the maximum soil temperature reached 29.5 °C. The maximum heat exchange capacity of one borehole reached 53 W/m and the maximum coefficient of performance (COP) reached 4.2, which shows the GSHP system is quite energy efficient. In addition, design and simulation software for the GSHP system was developed by authors. When putting the corresponding parameters of the GSHP system into the software, the simulated results well match the measured ones.

Modeling and energy simulation of the variable refrigerant flow air conditioning system with water-cooled condenser under cooling conditions

As a new system, variable refrigerant flow system with water-cooled condenser (water-cooled VRF) can offer several interesting characteristics for potential users. However, at present, its dynamic simulation simultaneously in association with building and other equipments is not yet included in the energy simulation programs. Based on the EnergyPlus's codes, and using manufacturer's performance parameters and data, the special simulation module for water-cooled VRF is developed and embedded in the software of EnergyPlus. After modeling and testing the new module, on the basis of a typical office building in Shanghai with water-cooled VRF system, the monthly and seasonal cooling energy consumption and the breakdown of the total power consumption are analyzed. The simulation results show that, during the whole cooling period, the fan-coil plus fresh air (FPFA) system consumes about 20% more power than the water-cooled VRF system does. The power comparison between the water-cooled VRF system and the air-cooled VRF system is performed too. All of these can provide designers some ideas to analyze the energy features of this new system and then to determine a better scheme of the air conditioning system.

Evaluation method of natural ventilation system based on thermal comfort in China

The distinctions between natural ventilation and mechanical ventilation system are explained. With the testing result of natural ventilation system of an office building in Shanghai, the irrationality of using energy-utilization coefficient to evaluate one natural ventilation system is discussed. Based on thermal comfort of natural ventilation environment, an evaluation method is then established and used to evaluate the testing result.

Evaluation of coupled outdoor and indoor thermal comfort environment and anthropogenic heat

With rapid urbanization, big cities in the south of China are progressively falling short of sustaining outdoor thermal comfort. In this paper, a thermal comfort and energy evaluation model is derived from revisions of previous study, to simulate and predict the interaction of coupled urban building-site climate and then the thermal comfort. The methodology of principal calculations is demonstrated first, then a hypothetical district of office buildings in Shanghai is selected. Dynamic on-site climate parameters, anthropogenic heat and indoor/outdoor SET* values, etc., are simulated and evaluated. The results show the variation of outdoor SET* values influenced by factors including canopy height, building coverage and air-conditioning set-point temperature.

Measurement and simulation of indoor air quality and energy consumption in two Shanghai office buildings with variable air volume systems

Two modern office buildings in Shanghai with typical variable air volume (VAV) systems were selected for research. Four separate spaces on a standard office floor in each building facing different directions (north, south, east, and west) were selected for thorough site measurements of outdoor airflow rates and indoor air quality (concentrations of CO 2 and PM 10) during typical days of the four seasons (summer, autumn, winter, spring). Computer simulations and calculations were also done of outdoor airflow rates and CO 2 concentrations in the four-test spaces on an hourly basis for the entire year. In addition to the site measurements, monthly electrical consumption for the two buildings was recorded or estimated. Simulations and calculations were performed of the buildings’ energy consumption and energy cost using two different outdoor air control strategies of a typical VAV system as well as a fan coil unit (FCU) system. The site-recorded data, or estimated data, and simulation results are compared and analyzed. The study reveals that in a VAV system, the outdoor airflow rate distributed to each zone varies greatly, especially during part-load hours, making it difficult to always ensure sufficient outdoor air in each zone and avoid indoor air quality (IAQ) problems. However, this problem can be prevented by using appropriate outdoor air control strategies—e.g. a fixed high level total outdoor airflow rate.

Grey Interrelated Evaluation of Indoor Air Quality in Buildings

In this paper, an analytical method for evaluating indoor air quality (IAQ) based on published values of prescribed upper limits for indoor air pollutants is presented. The method uses a ‘grey’ interrelated mathematical model developed from the ‘grey interrelated theory’. The model has been applied to actual measurements taken in office buildings in Shanghai. The analytical method provides a simpler and more accurate way of evaluating IAQ than other models and it provides a new theoretical base for such evaluations.

Grey Interrelated Evaluation of Indoor Air Quality in Buildings

In this paper, an analytical method for evaluating indoor air quality (IAQ) based on published values of prescribed upper limits for indoor air pollutants is presented. The method uses a 'grey' interrelated mathematical model developed from the 'grey interrelated theory'. The model has been applied to actual measurements taken in office buildings in Shanghai. The analytical method provides a simpler and more accurate way of evaluating IAQ than other models and it provides a new theoretical base for such evaluations.