A Bayesian Approach for Predicting Building Cooling and Heating Consumption and Applications in Fault Detection

Making a prediction typically involves dealing with uncertainties. The application of uncertainty analysis to buildings and HVAC (heating, ventilation and air conditioning) systems, however, remains limited. Most existing studies concentrate on the parameter uncertainty and parametric variability in building simulations for the design stage, and rely on Monte Carlo experiments to quantify this uncertainty. This dissertation aims to develop a rapid and direct method that is capable of quantifying uncertainty when predicting building cooling and heating consumption in the operation stage, while simultaneously capturing all sources of uncertainty and applying these to actual system operations. Gaussian Process regression, a Bayesian modeling method, is proposed for this purpose. The primary advantage of Gaussian Process regression is that it directly outputs a probability distribution that explicitly expresses prediction uncertainty. The predictive distribution covers uncertainty sources arising not only from parameter uncertainty and parametric variability, but also from modeling inadequacy and residual variability. By assuming a Gaussian input distribution and using Gaussian kernels, Gaussian Process regression takes parameter uncertainty and parametric variability into consideration without using the Monte Carlo method. This dissertation makes three main contributions. First, based on the observations from commissioning projects for approximately twenty campus buildings, some of the important uncertainties and typical problems in variable air volume system (VAV) operations are identified. Second, Gaussian Process regression is used to predict building cooling and heating consumption and to evaluate the impact of parametric variability of system control related variables. Third, a method for automated fault detection that uses Gaussian Process regression to model baselines is developed. By using the uncertainty outputs from the Gaussian Process regression together with Bayes classifiers and probabilistic graphical models, the proposed method can detect whether system performance is normal or faulty at the system component level or the whole building level with a high degree of accuracy

A statistical analysis of multiple temperature proxies: Are reconstructions of surface temperatures over the last 1000 years reliable?

Predicting historic temperatures based on tree rings, ice cores, and other natural proxies is a difficult endeavor. The relationship between proxies and temperature is weak and the number of proxies is far larger than the number of target data points. Furthermore, the data contain complex spatial and temporal dependence structures which are not easily captured with simple models. In this paper, we assess the reliability of such reconstructions and their statistical significance against various null models. We find that the proxies do not predict temperature significantly better than random series generated independently of temperature. Furthermore, various model specifications that perform similarly at predicting temperature produce extremely different historical backcasts. Finally, the proxies seem unable to forecast the high levels of and sharp run-up in temperature in the 1990s either in-sample or from contiguous holdout blocks, thus casting doubt on their ability to predict such phenomena if in fact they occurred several hundred years ago. We propose our own reconstruction of Northern Hemisphere average annual land temperature over the last millennium, assess its reliability, and compare it to those from the climate science literature. Our model provides a similar reconstruction but has much wider standard errors, reflecting the weak signal and large uncertainty encountered in this setting.Comment: Published in at http://dx.doi.org/10.1214/10-AOAS398 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Intelligent energy storage management trade-off system applied to Deep Learning predictions

The control of the electrical power supply is one of the key bases to reach the sustainable development goals set by United Nations. The achievement of these objectives encourages a dual strategy of creation and diffusion of renewable energies and other technologies of zero emission. Thus, meet the emerging necessities require, inevitably, a significant transformation of the building sector to improve the design of the electrical infrastructure. This improvement should be linked to advanced techniques that allows the identification of complex patterns in large amount of data, such as Deep Learning ones, in order to mitigate potential uncertainties. Accurate electricity and energy supply prediction models, in combination with storage systems will be reflected directly in efficiency improvements in buildings. In this paper, a branch of Deep Learning models, known as Standard Neural Networks, are used to predict electricity consumption and photovoltaic generation with the purpose of reduce the energy wasted, by managing the storage system using Reinforcement Learning technique. Specifically, Deep Reinforcement Learning is applied using the Deep Q-Learning agent. Furthermore, the accuracy of the predicted variables is measured by means of normalized Mean Bias Error (nMBE), and normalized Root Mean Squared Error (nRMSE). The methodologies developed are validated in an existing building, the School of Mining and Energy Engineering located on the Campus of the University of Vigo.Agencia Estatal de Investigación | Ref. TED2021-130677B-I00Financiado para publicación en acceso aberto: Universidade de Vigo/CISU

Probabilistic and artificial intelligence modelling of drought and agricultural crop yield in Pakistan

Pakistan is a drought-prone, agricultural nation with hydro-meteorological imbalances that increase the scarcity of water resources, thus, constraining water availability and leading major risks to the agricultural productivity sector and food security. Rainfall and drought are imperative matters of consideration, both for hydrological and agricultural applications. The aim of this doctoral thesis is to advance new knowledge in designing hybridized probabilistic and artificial intelligence forecasts models for rainfall, drought and crop yield within the agricultural hubs in Pakistan. The choice of these study regions is a strategic decision, to focus on precision agriculture given the importance of rainfall and drought events on agricultural crops in socioeconomic activities of Pakistan. The outcomes of this PhD contribute to efficient modelling of seasonal rainfall, drought and crop yield to assist farmers and other stakeholders to promote more strategic decisions for better management of climate risk for agriculturalreliant nations