15,564 research outputs found
Modeling and Optimization of Complex Building Energy Systems with Deep Neural Networks
Modern buildings encompass complex dynamics of multiple electrical,
mechanical, and control systems. One of the biggest hurdles in applying
conventional model-based optimization and control methods to building energy
management is the huge cost and effort of capturing diverse and temporally
correlated dynamics. Here we propose an alternative approach which is
model-free and data-driven. By utilizing high volume of data coming from
advanced sensors, we train a deep Recurrent Neural Networks (RNN) which could
accurately represent the operation's temporal dynamics of building complexes.
The trained network is then directly fitted into a constrained optimization
problem with finite horizons. By reformulating the constrained optimization as
an unconstrained optimization problem, we use iterative gradient descents
method with momentum to find optimal control inputs. Simulation results
demonstrate proposed method's improved performances over model-based approach
on both building system modeling and control
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Building thermal load prediction through shallow machine learning and deep learning
Building thermal load prediction informs the optimization of cooling plant and thermal energy storage. Physics-based prediction models of building thermal load are constrained by the model and input complexity. In this study, we developed 12 data-driven models (7 shallow learning, 2 deep learning, and 3 heuristic methods) to predict building thermal load and compared shallow machine learning and deep learning. The 12 prediction models were compared with the measured cooling demand. It was found XGBoost (Extreme Gradient Boost) and LSTM (Long Short Term Memory) provided the most accurate load prediction in the shallow and deep learning category, and both outperformed the best baseline model, which uses the previous day's data for prediction. Then, we discussed how the prediction horizon and input uncertainty would influence the load prediction accuracy. Major conclusions are twofold: first, LSTM performs well in short-term prediction (1 h ahead) but not in long term prediction (24 h ahead), because the sequential information becomes less relevant and accordingly not so useful when the prediction horizon is long. Second, the presence of weather forecast uncertainty deteriorates XGBoost's accuracy and favors LSTM, because the sequential information makes the model more robust to input uncertainty. Training the model with the uncertain rather than accurate weather data could enhance the model's robustness. Our findings have two implications for practice. First, LSTM is recommended for short-term load prediction given that weather forecast uncertainty is unavoidable. Second, XGBoost is recommended for long term prediction, and the model should be trained with the presence of input uncertainty
Efficient State-Space Inference of Periodic Latent Force Models
Latent force models (LFM) are principled approaches to incorporating
solutions to differential equations within non-parametric inference methods.
Unfortunately, the development and application of LFMs can be inhibited by
their computational cost, especially when closed-form solutions for the LFM are
unavailable, as is the case in many real world problems where these latent
forces exhibit periodic behaviour. Given this, we develop a new sparse
representation of LFMs which considerably improves their computational
efficiency, as well as broadening their applicability, in a principled way, to
domains with periodic or near periodic latent forces. Our approach uses a
linear basis model to approximate one generative model for each periodic force.
We assume that the latent forces are generated from Gaussian process priors and
develop a linear basis model which fully expresses these priors. We apply our
approach to model the thermal dynamics of domestic buildings and show that it
is effective at predicting day-ahead temperatures within the homes. We also
apply our approach within queueing theory in which quasi-periodic arrival rates
are modelled as latent forces. In both cases, we demonstrate that our approach
can be implemented efficiently using state-space methods which encode the
linear dynamic systems via LFMs. Further, we show that state estimates obtained
using periodic latent force models can reduce the root mean squared error to
17% of that from non-periodic models and 27% of the nearest rival approach
which is the resonator model.Comment: 61 pages, 13 figures, accepted for publication in JMLR. Updates from
earlier version occur throughout article in response to JMLR review
Overview of methods to analyse dynamic data
This book gives an overview of existing data analysis methods to analyse the dynamic data obtained from full scale testing, with their advantages and drawbacks. The overview of full scale testing and dynamic data analysis is limited to energy performance characterization of either building components or whole buildings.
The methods range from averaging and regression methods to dynamic approaches based on system identification techniques. These methods are discussed in relation to their application in following in situ measurements:
-measurement of thermal transmittance of building components based on heat flux meters;
-measurement of thermal and solar transmittance of building components tested in outdoor calorimetric test cells;
-measurement of heat transfer coefficient and solar aperture of whole buildings based on co-heating or transient heating tests;
-characterisation of the energy performance of whole buildings based on energy use monitoring
Building energy performance characterisation based on dynamic analysis and co-heating test
A demonstration zero-carbon neighborhood is being raised in the city of Kortrijk, Belgium in the framework of the ECO-Life project within the CONCERTO initiative. A holistic approach is applied to achieve the zero-carbon targets, considering all aspects that are relevant for energy supply. Accordingly, alongside the integration of renewable energy sources in the community, a low-temperature district heating system is being implemented to cover the heat demand. In this context, full scale testing of building thermal performances, by use of a co-heating test and flux measurements, can be useful to analyze the thermal performance of the building envelope in situ. For that reason, as part of a more general study regarding low-energy building, co-heating test, blower-door test and flux measurements in several apartments were executed. Therefore, the paper focuses on characterization of the thermal dynamic behavior of an apartment, as a first approximation of data analysis of a monitoring system involving whole buildings. In addition, in the present study, the capability of linear regression techniques to characterize the thermal behavior of a newly built low-energy apartment in Belgium is investigated. The strengths and weaknesses of different models are identified. The limitation and possibilities of regression models are evaluated in the face of their applicability as a simplified building equation model. The identified model structure is going to be used within a complex simulation model of an entire district heating system with around 200 dwelling. Finally, the potential of this kind of regression models to be used as part of the operational control scheme of a district heating system is presented
Support Vector Machine in Prediction of Building Energy Demand Using Pseudo Dynamic Approach
Building's energy consumption prediction is a major concern in the recent
years and many efforts have been achieved in order to improve the energy
management of buildings. In particular, the prediction of energy consumption in
building is essential for the energy operator to build an optimal operating
strategy, which could be integrated to building's energy management system
(BEMS). This paper proposes a prediction model for building energy consumption
using support vector machine (SVM). Data-driven model, for instance, SVM is
very sensitive to the selection of training data. Thus the relevant days data
selection method based on Dynamic Time Warping is used to train SVM model. In
addition, to encompass thermal inertia of building, pseudo dynamic model is
applied since it takes into account information of transition of energy
consumption effects and occupancy profile. Relevant days data selection and
whole training data model is applied to the case studies of Ecole des Mines de
Nantes, France Office building. The results showed that support vector machine
based on relevant data selection method is able to predict the energy
consumption of building with a high accuracy in compare to whole data training.
In addition, relevant data selection method is computationally cheaper (around
8 minute training time) in contrast to whole data training (around 31 hour for
weekend and 116 hour for working days) and reveals realistic control
implementation for online system as well.Comment: Proceedings of ECOS 2015-The 28th International Conference on
Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy
Systems , Jun 2015, Pau, Franc
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