https://waterfootprint.org/media/downloads/Chapagain-and-Orr-2009_1.pdf

An improved water footprint methodology linking global consumption to local water resources: a case of Spanish tomatoes.

The appropriate application of advanced control strategies in Heating, Ventilation, and Air-conditioning (HVAC) systems is key to improving the energy efficiency of buildings. Significant advances have been made in the past decades on model development to provide better control over the energy consumption of system components while simultaneously ensuring a satisfactory indoor environment in terms of thermal comfort and indoor air quality. Yet it is an ongoing challenge to select and implement the best-suited modeling technique for improving the control strategy of HVAC systems. For the development of modeling research it is important that the building research community is informed about the role, application, merits, shortcomings and outcomes of different modeling techniques used in HVAC systems. Even though several review articles have been published on modeling techniques, the weaknesses and strengths of these modeling techniques, along with performances of developed models associated with research studies, have rarely been identified. This study presents a critical review of current modeling techniques used in HVAC systems regarding their applicability and ease of acceptance in practice and summarizes the strengths, weaknesses, applications and performance of these modeling techniques. Additionally, the performance and outcome of some of the developed models used in real world HVAC systems have been discussed. From the extensive critical review it is evident that almost every model has a major/minor shortcoming generated from assumptions, unmeasured disturbances or uncertainties in some system properties. This review aims at highlighting the shortcomings of existing application-based research on HVAC systems, and accordingly, recommendations are presented to improve the performance of building HVAC systems.

Modeling techniques used in building HVAC control systems: A review

This paper reviews the most used thermal comfort models and indicators with their variants, discussing their usage in control problems referring to energy management in indoor applications The first part addresses the recent literature referring to the thermal comfort concepts, models of human thermal comfort, thermal comfort models and indicators, thermal comfort standards, control systems, optimisation methods, and practical assessments Then, the ambient and personal parameters used to represent thermal comfort and thermal sensation are recalled The following part reviews the definitions and usage of a number of thermal comfort indices, mainly related to the Predicted Mean Vote ( PMV ), the Actual Mean Vote ( AMV ), and the Predicted Percentage Dissatisfied ( PPD ), with their modifications and variants, indicating a number of applications to different situations in indoor environments The last part reviews the thermal comfort models used to define control strategies in indoor applications, discussing the characteristics and parameters of models based on artificial neural networks, autoregressive variants, fuzzy control, and hybrid models combining different approaches The characteristics of these models and their usage to predict the indoor air temperature and the PMV index are discussed with reference to the identification of the several inputs used in relevant literature contributions

A review of thermal comfort models and indicators for indoor environments

Prediction of room temperature and relative humidity by autoregressive linear and nonlinear neural network models for an open office

Review: Effect of ventilator configuration on the distributed climate of greenhouses: A review of experimental and CFD studies

Water requirement of drip irrigated tomatoes grown in greenhouse in tropical environment

Modelling of tropical greenhouse temperature by auto regressive and neural network models

Microclimate and Air Exchange Rates in Greenhouses covered with Different Nets in the Humid Tropics

Optimization of ventilation opening area of a naturally ventilated net greenhouse in a humid tropical environment

An investigation on the effect of the use of nets with different mesh-sizes on the internal
microclimate and ventilation rate in greenhouses located on the humid tropics was carried
out. Three greenhouses (each measuring 10 m wide × 20 m long) were constructed and
covered with a plastic film on the roof, and different insect proof nets on the sidewalls,
respectively. Net sizes of 40-mesh, 52-mesh and 78-mesh were used. Water vapour,
transpired from 300 tomatoes cultivated in each greenhouse, was used to determine the
ventilation rate. In addition, an energy balance method which offers a simple, rapid and
accurate way to predict ventilation rate was developed based on common climatic data and
used in this study. A good agreement (R2 = 0.85) was obtained between two methods.
Statistically, the use of insect screens with different mesh-sizes had a significant effect on
ventilation rate and internal microclimate. The reduction of ventilation rate about 50% and
35% for the 78-mesh and 52-mesh greenhouses, respectively was obtained compared to the
40-mesh greenhouse. Consequently, the internal air temperature was also increased by 1 to 3
°C. Although, a small temperature difference was observed, the absolute humidity among
treatments was significantly different. The use of a higher mesh-size resulted in more
humidity. Ventilation rate and temperature rise in the greenhouses were strongly correlated to
the net porosity. Since their correlations were good in agreement, the simple equation derived
from the experiment will be very useful in predicting air exchange rate and temperature rise
when a new type of net is applied.

H.J. Tantau

Papers

Water requirement of drip irrigated tomatoes grown in greenhouse in tropical environment

Modelling of tropical greenhouse temperature by auto regressive and neural network models

Microclimate and Air Exchange Rates in Greenhouses covered with Different Nets in the Humid Tropics

Optimization of ventilation opening area of a naturally ventilated net greenhouse in a humid tropical environment

Influence of Insect Screens with Different Mesh Sizes on Ventilation Rate and Microclimate of Greenhouses in the Humid tropics