建筑暖通空调系统节能设计中绿色理念的运用

在建筑工程中,暖通空调系统的能耗较高,为降低该系统的能耗,可在节能设计中引入绿色理念。从分析建筑暖通空调节能设计引入绿色理念的重要意义入手,阐述了基于绿色理念的暖通空调系统设计原则,以及绿色理念在建筑暖通空调系统节能设计中的运用,最后论述了工程应用实例。     

建筑暖通空调设计及节能分析

当前建筑暖通空调的能耗在中国的能源消耗中的占比为10%左右,考虑到中国采暖用冷的城镇人口占比较低,因此实际的建筑暖通空调能耗占比已经相当高了。为了响应国家的低碳发展政策,对建筑暖通空调系统的节能设计提出了更高的要求。暖通设计工作者要根据不同的建筑类型、特点和用途对空调系统进行差异化设计,其目的就是达到既要满足建筑的用能需求又能使能耗最小化。从当前暖通空调设计发展现状着眼,对建筑暖通空调的设计及节能进行分析,尽可能地降低能源消耗,促进暖通空调的节能发展。     

暖通空调系统节能探讨

主要介绍了暖通空调系统节能的有效途径，阐述了在设计上施工上体会，从节能 角度进行设计方案的比较和优选，开展了冷热回收的综合利用，解决了暖通空调系统在运行过 程中存在的问题。     

太原市东岳大厦暖通空调设计

叙述了太原市东岳大厦暖通空调系统的设计.针对各房间的不同建筑特点和使用功能,结合具体情况采用了相应的空调方式,在不同区域分别采用全空气一次回风系统和风机盘管加新风系统,兼顾了暖通空调系统的功能性和节能要求,指出,空调排风与防排烟联合系统的设置,保证两系统各自运行的同时节约了初投资；冷却塔设置在住宅屋面,提升了住宅区的建筑声环境,减少了对住户的干扰；住宅区分户采暖的方式更为简单且便于控制调节.     

建筑环境与暖通空调节能

本文针对暖通空调节能的趋势,分析了建筑环境对暖通空调系统的影响,提出从建筑环境方面考虑问题是暖通空调节能的必要途径。     

建筑物供暖空调系统节能控制仿真

为了解决暖通空调控制系统的时滞、时变等非线性特征使其控制效果变差的问题,设计了在线辨识对象模型和基于SMITH预估器的自校正控制算法。实现了在线闭环辨识暖通空调特性参数,在获得相应模型后以SMITH预估器补偿时滞参数从而抵消各种消极状况,优化PI控制器加强其鲁棒性能。仿真结果表明所设计的在线辨识模型和控制算法取得了良好的控制效果并具备可行性。     

建筑本体(热工)、建筑总体及暖通空调节能设计的主旨与区别

建筑本体节能设计是建筑节能设计的基础部分,建筑热工节能设计是建筑本体节能设计的主要组成部分;暖通空调等建筑设备节能设计是建筑节能设计的终端部分,建筑总体节能设计由基础部分和终端部分组成。建筑本体节能设计旨在控制暖通空调等建筑设备的用能负荷,建筑热工节能设计旨在控制围护结构暖通空调负荷,暖通空调等建筑设备节能设计旨在控制其供用能系统效率,建筑总体节能设计旨在控制整个建筑物的能耗。《对公共建筑节能设计标准宣贯辅导教材》等相关文献中对上述几种节能设计(参数)的含义、功用与区别表述不甚清晰的部分进行了分析和讨论。     

基于建筑环境的空调系统节能分析

针对暖通空调节能的趋势 ,分析了建筑环境对暖通空调系统的影响 ,提出从建筑环境方面考虑问题是暖通空调节能的必要途径 ,概括地介绍了空调能源的发展方向和空调节能的多种手法     

发电厂中央空调系统的节能设计

分析了电厂空调系统存在的问题，在介绍变频控制节能原理的基础上，对某电厂主厂房空调系统改造一期工程中的节能设计进行了分析。实践证明，该设计能够以最小的成本实现节能降耗的目的，对同类空调系统的设计具有借鉴作用。     

民用建筑暖通空调设计中的问题及对策研究

如今,广大人民群众的物质生活水平实现大幅度提升,而暖通空调系统在民用建筑中得到了广泛应用,其设计直接关系到空调系统的运行质量。然而,在实际应用中,暖通空调设计存在诸多问题,覆盖设备选型、供能方式、冷热负荷计算等各个方面,进而影响到人们的体验。基于此,对设计中的问题及对策进行研究。     

Progress and methodologies of lifecycle commissioning of HVAC systems to enhance building sustainability

Building energy consumption keeps rising in recent years due to growth in population, increasing demand for healthy, comfort and productive indoor environment, global climate changing, etc. Nowadays, the contribution from buildings toward global energy consumption is approximately 40%. Most of energy use in buildings is for the provision of heating, ventilation and air conditioning (HVAC). High-level performance of HVAC systems in building lifecycle is critical to building sustainability.As a quality-oriented process, commissioning has been recognized as a valid means to improve performance of buildings and HVAC systems in both energy and environment aspects and should be conducted regularly or continuously throughout the whole building lifecycle. At the same time, building automation systems (BAS) are now standard in most modern buildings. Besides automatic monitoring and control of building services systems, automatic commissioning is a new expectation on modern BAS to save labor, time and cost required by manual commissioning and improve the effectiveness of commissioning. This paper firstly takes a brief look at current situation of building commissioning in research and application world wide, and then summarizes state-of-the-art techniques for automatic commissioning of HVAC systems. It is concluded that, to maximize benefits from commissioning for enhancing building sustainability, more efforts should be made to develop automatic commissioning tools which can be integrated with modern BAS.     

以PMV为基础的模糊控制器在VAV空调系统中的应用

通过对以热舒适性指标ＰＭＶ为参数的模糊控制方法和以固定室内温度的 ＰＩＤ控制方法的比较,得出了前者不但能够达到满足室内人员的热舒适性要求, 更能节省能量消耗的特点。在空调系统模拟软件ＨＶＡＣＳＩＭ＋的辅助下,对这 一结论进行了验证。     

A cost‐effective operating strategy to reduce energy consumption in a HVAC system

The operation of the building heating, ventilating, and air conditioning (HVAC) system is a critical activity in terms of optimizing the building's energy consumption, ensuring the occupants' comfort, and preserving air quality. The performance of HVAC systems can be improved through optimized supervisory control strategies. Set points can be adjusted by the optimized supervisor to improve the operating efficiency. This paper presents a cost‐effective building operating strategy to reduce energy costs associated with the operation of the HVAC system. The strategy determines the set points of local‐loop controllers used in a multi‐zone HVAC system. The controller set points include the supply air temperature, the supply duct static pressure, and the chilled water supply temperature. The variation of zone air temperatures around the set point is also considered. The strategy provides proper set points to controllers for minimum energy use while maintaining the required thermal comfort. The proposed technology is computationally simple and suitable for online implementation; it requires access to some data that are already measured and therefore available in most existing building energy management and control systems. The strategy is evaluated for a case study in an existing variable air volume system. The results show that the proposed strategy may be an excellent means of reducing utility costs associated with maintaining or improving indoor environmental conditions. It may reduce energy consumption by about 11% when compared with the actual strategy applied on the investigated existing system. Copyright © 2007 John Wiley & Sons, Ltd.     

Real‐time tuning of PI controllers in HVAC systems

The problem of tuning single‐loop controllers in heating, ventilating and air conditioning (HVAC) systems is explored. The HVAC process was described by a first‐order‐plus‐dead‐time (FOPDT) model. By using recursive least squares method, the model parameters were updated while the system remained in closed‐loop. The H_∞ loop‐shaping tuning rules published in the literature were transformed to discrete‐time tuning rules and were implemented in an adaptive PI control strategy. The methodology was applied to a discharge air temperature (DAT) control system. The output responses of adaptive PI controller were compared with a LQR optimal adaptive controller. Simulation results show that the adaptively tuned PI controller is able to track setpoint changes very well in the presence of changes in plant parameters, disturbances and external noise acting on the system. Copyright © 2004 John Wiley & Sons, Ltd.     

Evaluation of operation characteristics in multiple interconnection of PV systems

A method for evaluating the operation characteristic of grid-connected PV systems in multiple interconnection was proposed and a suppression of PV electric energy which is reduced by an automatic voltage control unit was estimated using a yearly scale simulation. The automatic voltage control unit is one of the PV inverter functions. In Japan, PV systems must be provided with this function to maintain within 101 V±6 V for the standard voltage of 100 V according to the technical recommendations. The automatic control voltage unit adjusts the distribution-line voltage at a connected point using leading reactive power or active power. Especially, the adjustment of active power will cause a suppression of PV electric energy.     

Global optimization for overall HVAC systems––Part II problem solution and simulations

This paper presents the solution for the global optimization problem for overall heating, ventilating and air conditioning (HVAC) systems using a modified genetic algorithm. The whole implementation procedure of the proposed optimal method is provided. Simulation studies for a pilot scale centralized HVAC plant by the proposed optimal method show that the proposed method indeed improves the system performance significantly compared with traditional control strategies.     

The map of energy flow in HVAC systems

Heating, ventilation and air conditioning (HVAC) systems are the most energy consuming building services representing approximately half of the final energy use in the building sector and between one tenth and one fifth of the energy consumption in developed countries. Despite their significant energy use, there is a lack of a consistent and homogeneous framework to efficiently guide research and energy policies, mainly due to the complexity and variety of HVAC systems but also to insufficient rigour in their energy analysis. This paper reviews energy related aspects of HVAC systems with the aim of establishing a common ground for the analysis of their energy efficiency. The paper focuses on the map of energy flow to deliver thermal comfort: the HVAC energy chain. Our approach deals first with thermal comfort as the final service delivered to building occupants. Secondly, conditioned spaces are examined as the systems where useful heat (or coolth) is degraded to provide comfort. This is followed by the analysis of HVAC systems as complex energy conversion devices where energy carriers are transformed into useful heat and coolth, and finally, the impact of HVAC energy consumption on energy resources is discussed.     

Energy saving by integrated control of natural ventilation and HVAC systems using model guide for comparison

Integrated control by controlling both natural ventilation and HVAC systems based on human thermal comfort requirement can result in significant energy savings. The concept of this paper differs from conventional methods of energy saving in HVAC systems by integrating the control of both these HVAC systems and the available natural ventilation that is based on the temperature difference between the indoor and the outdoor air. This difference affects the rate of change of indoor air enthalpy or indoor air potential energy storage. However, this is not efficient enough as there are other factors affecting the rate of change of indoor air enthalpy that should be considered to achieve maximum energy saving. One way of improvement can be through the use of model guide for comparison (MGFC) that uses physical-empirical hybrid modelling to predict the rate of change of indoor air potential energy storage considering building fabric and its fixture. Three methods (normal, conventional and proposed) are tested on an identical residential building model using predicted mean vote (PMV) sensor as a criterion test for thermal comfort standard. The results indicate that the proposed method achieved significant energy savings compared with the other methods while still achieving thermal comfort.     

Application of neural network for the modeling and control of evaporative condenser cooling load

Artificial neural network (ANN), in comparison with PID controllers which have broad applications in the highly complex HVAC systems, has recently received more attention. The present paper includes thermodynamic modeling of an evaporative condenser under steady state and transient state conditions for establishing control of thermal capacity, using Artificial neural network. To train the system under dynamic condition, predictive neural network, capable of understanding dynamic behavior and predicting the preset output is used. The principle operation of such neural networks is based on the reduction of gradients of errors existing between the predicted output and the actual output of the system. To control the system thermal capacity, neural controller based on training received from the reduction of gradients between the output controller and the ideal output, is used. Results obtained during present investigation indicate that artificial neural network controller is suitable substitute for PID controllers for thermal systems.     

Virtual models of indoor-air-quality sensors

A data-driven approach for modeling indoor-air-quality (IAQ) sensors used in heating, ventilation, and air conditioning (HVAC) systems is presented. The IAQ sensors considered in the paper measure three basic parameters, temperature, CO₂, and relative humidity. Three models predicting values of IAQ parameters are built with various data mining algorithms. Four data mining algorithms have been tested on the HVAC data set collected at an office-type facility. The computational results produced by models built with different data mining algorithms are discussed. The neural network (NN) with multi-layer perceptron (MLP) algorithms produced the best results for all three IAQ sensors among all algorithms tested. The models built with data mining algorithms can serve as virtual IAQ sensors in buildings and be used for on-line monitoring and calibration of the IAQ sensors. The approach presented in this paper can be applied to HVAC systems in buildings beyond the type considered in this paper.