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See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/320197023 A Data-Driven Modelling Approach for Large Scale Demand Profiling of Residential Buildings Conference Paper · August 2017 CITATIONS 0 READS 173 5 authors, including: Some of the authors of this publication are also working on these related projects: THERM - THrough life Energy and Resource Modelling View project CiNERGY - Smart Cities with Sustainable Energy Systems View project Giovanni Tardioli Integrated Environmental Solutions 5 PUBLICATIONS 19 CITATIONS SEE PROFILE Ruth Kerrigan 12 PUBLICATIONS 39 CITATIONS SEE PROFILE All content following this page was uploaded by Giovanni Tardioli on 04 October 2017. The user has requested enhancement of the downloaded file.

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See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/320197023

A Data-Driven Modelling Approach for Large Scale Demand Profiling of

Residential Buildings

Conference Paper · August 2017

CITATIONS

0READS

173

5 authors, including:

Some of the authors of this publication are also working on these related projects:

THERM - THrough life Energy and Resource Modelling View project

CiNERGY - Smart Cities with Sustainable Energy Systems View project

Giovanni Tardioli

Integrated Environmental Solutions

5 PUBLICATIONS   19 CITATIONS   

SEE PROFILE

Ruth Kerrigan

12 PUBLICATIONS   39 CITATIONS   

SEE PROFILE

All content following this page was uploaded by Giovanni Tardioli on 04 October 2017.

The user has requested enhancement of the downloaded file.

Page 2: A Data-Driven Modelling Approach for Large Scale Demand

A Data-Driven Modelling Approach for Large Scale Demand Profilingof Residential Buildings

Giovanni Tardioli1,2, Ruth Kerrigan1, Mike Oates1, James O’Donnell2, Donal Finn2

1: Integrated Environmental Solutions (IES) R&D, Glasgow, UK2: School of Mechanical & Materials Engineering, University College Dublin, Dublin, Ireland

AbstractIn this paper the traditional use of data-driven models(DDM) as forecasting tools is coupled with paramet-ric simulation to create a building modelling frame-work for demand profiling of a large number of build-ings of the same typology. Most studies to date util-ising DDM have been conducted on single buildings,with less evidence of the role that DDM may haveas a modelling technique for application at scale.The proposed methodology is based on the use ofa simulation-based building energy modelling tooland a parametric simulator to create a large datasetconsisting of 4096 different building model scenarios.Three DDM techniques are utilised; Support VectorMachines, Neural Networks and Generalised LinearModels, these are trained and tested using the gener-ated simulation dataset. Results, at an hourly reso-lution, show that DDM approaches can correctly em-ulate the outputs of the building simulation softwarewith mean absolute error ranging from 4 to 9 percentfor different DDM algorithms.

IntroductionModelling building energy use at a high spatio-temporal resolution and at large scale is a computa-tional and resource intensive problem. Several issuesincrease the difficulty in modelling a vast number ofbuildings, these include but are not limited to: het-erogeneity of the built environment, possible lack ofbuilding data, high computational requirements for asimulated representation of the building stock, uncer-tainties related to building information and modellingprocedures, linking of structured and unstructureddata, complexity in representing interconnected phys-ical phenomena and difficulties in providing scalableand replicable solutions. Overcoming all these issuesrequires substantial research effort.Simulating building consumption at different levels ofspatial and temporal resolution, facilitates the adop-tion of a variety of energy efficient technologies andoperations, ranging from deep retrofit interventionsto demand side management actions. For this reason,different levels of spatial analyses may be required,e.g. national, regional, urban, district and singlebuilding level. Based on the objective of the anal-

ysis, different time scales may also be appropriate,i.e. annual, monthly, daily, hourly and sub-hourly.On one hand, techniques for modelling and analysingsingle building energy use are mature and well consol-idated; on the other, modelling at fine time resolutionand at large scale, such as at district or city level, isan emerging field where there is still a lack of vali-dated procedures and standardisation Reinhart andDavila (2016).In recent years, different modelling techniques havebeen proposed for the representation of building en-ergy use at large scale. These methods and tech-niques, use mostly a bottom-up modelling approachand can be divided into three major categories:the engineering or physical approach, the hybridapproach and the data driven modelling approachEicker et al. (2015). These techniques, were first usedfor single building applications but have been recentlyadopted for studies involving a vast numbers of build-ings Swan and Ugursal (2009). In particular the engi-neering method and the hybrid approach find severalapplications in the context of large scale modellingFonseca et al. (2016), Robinson et al. (2009). Otherlarge scale studies employ the use of representativebuilding energy models, usually called archetypes,to represent a portion of the building stock Ballar-ini et al. (2014). These representative models areusually identified through statistical approaches butmore recently through clustering techniques. Thesetechniques aim to isolate building groups sharing sim-ilarities and permit the identification of the most rep-resentative element of the cluster.Most of the studies on data driven models (DDM)focus on single building level applications; the major-ity of these studies investigate DDM as forecasters ofindividual building electric and heating consumption.In this context DDM are employed for demand sidemanagement and demand response analysis Burgerand Moura (2015) or in predictive control systemsFerreira et al. (2012). Few studies focus on the use ofDDM at large scale and when they do they analyseaggregated groups of buildings or predictive methodsfor yearly or monthly estimated consumption. Otherstudies show that DDM can exploit large scale mod-elling techniques to provide early design consump-

Page 3: A Data-Driven Modelling Approach for Large Scale Demand

tion information. There are currently no methodolo-gies based on data-driven methods, which are used asbuilding demand profiling techniques at large scale.DDM characteristics could be exploited to alleviatethe modelling burdens associated with large scale ac-curate simulations at district or urban level wheresimplified methods and computational issues are ofinterest.The aim of the current paper is to describe a scal-able methodology based on the use of DDM as a de-mand modelling technique for large numbers of build-ings and to test the proposed approach on a casestudy. The methodology is based on the exploita-tion of a representative building energy model andthe use of parametric simulation to create a databasefor the training of the DDM. The representative en-ergy model could be representative for example of theoutcome of a clustering analysis procedure conductedon an urban case study Ghiassi et al. (2015).The paper is structured as follows. Initially, a com-prehensive review of data driven modelling techniquesutilised in the building energy domain is presented;then, the research ”gap” is identified and described;following this, the research methodology is discussedand explained in detail as well as the underliningcontribution and novelty of the present work; themethodology is then tested on a case study and fi-nally a description of the main outcomes of this ap-proach is provided. The strengths and limitations ofthe presented approach are discussed and scope forfurther research is presented taking into considera-tion the deployment of the technique at an urban ordistrict level.

State of the artThere are many examples of the use of DDM in thebuilding energy sector. Table 1 provides an overviewof the main applications of DDM. Specifically, thetable provides information regarding the algorithmsemployed and summarises the main inputs, outputsand resolution of the data. Furthermore, Table 1 pro-vides a useful insight regarding the scale of analysisand level of aggregation of the case studies.The majority of the studies concerning DDM are re-lated to single building level applications. In thisregard, DDM are employed mostly as forecasters ofbuilding energy consumption. Edwards et al. (2012)compared seven different machine learning algorithmstrained on 15 minute consumption data of a residen-tial case study. Jain et al. (2014) developed a sensor-based forecasting model using support vector regres-sion (SVR), for a multi-family residential building un-derlining the impact of temporal (i.e., daily, hourly,10 min intervals) and spatial (i.e., whole building,by floor, by unit) granularity. Fan et al. (2014) de-veloped an ensemble model for a commercial build-ing for predicting next-day energy consumption andpeak power demand, using a genetic algorithm for

parametric optimisation. Macas et al. (2016) pro-posed a technique based on artificial neural networks(ANN) to predict total heating energy consumption,internal air temperature and aggregated thermal dis-comfort 12 hours ahead, for operational cost reduc-tion of an office building. Mai et al. (2014) presentedan hourly electric load forecasting model for an of-fice building based on a neural network using out-door weather data and historical load data as inputs,proposing a simplified parameter tuning procedure.Yang et al. (2014) proposed a model to predict energyconsumption for a chiller using historic building oper-ation data and weather forecast information. Paudelet al. (2014) presented a predictive model of an insti-tutional building to predict heating demand with oc-cupancy profiles and operational heating power levelsfor short time horizon predictions. Kapetanakis et al.(2015) developed DDM for forecasting a commercialbuilding heating loads based building energy manage-ment systems variables and weather data, presentingan inputs selection technique. Li and Wen (2014)proposed a methodology to develop building energyestimation models using frequency domain spectraldensity analysis for a commercial building.Compared to single building level applications, thereare fewer studies which involve the use of DDM ongroups of buildings. Consumption data are usuallyaggregated when the study is performed on more thanone building. Data are typically gathered from elec-tric or heating network substations or from buildingmanagement systems controlling the entire group ofbuildings. Some relevant examples in this contextare studies conducted on university campuses Powellet al. (2014). Escriva-Escriva et al. (2011) created anANN model for short-term prediction of total powerconsumption for a large group of university buildings.Jurado et al. (2015) proposed a hybrid methodologyfor three university buildings which combines featureselection based on entropy measures and DDM. Jo-vanovic and Zivkovic (2014) proposed a method forpredicting heating energy consumption of 35 build-ings using an ANN. Humeau (2013) studied statisti-cal relations between consumption series data by clus-tering houses according to their consumption profilesand using DDM to estimate aggregate district con-sumption. Other applications of the use of DDM atan aggregated level are typically performed by utilitycompanies which employ data analysis on smart me-tering systems and the use of DDM to estimate peakpower demand for entire districts. This helps utilitiesforecast the supply requirements with respect to buy-ing or trading on energy markets at convenient pricesor to identify stressed points of the network and toplan ahead network maintenance and upgrades.At district or city scale, Nouvel et al. (2015)) andHoward et al. (2012) focused on forecasting buildingconsumption for many single buildings at a yearly res-olution. Williams and Gomez (2016) proposed an ap-

Page 4: A Data-Driven Modelling Approach for Large Scale Demand

Table 1: DDM applications from single buildings to large groups: time resolution, algorithms, inputs and outputs

Case studies and modelsInputs Output

Weather variables Time variables Other Consumption

Ref. Case Study Algorithms Resolution

Out

Air

tem

p

Inte

rnal

Air

tem

p

Glo

bal

radi

atio

n

Win

dsp

eed

Win

ddi

rect

ion

Rel

ativ

ehu

mid

ity

Day

type

Hou

rof

the

day

Pas

tco

ns.

Oth

er

Electrical (E)Thermal - Heating (T.H)Thermal - Cooling (T.C.)

MLR ANN SVM OtherEdwardset al. (2012)

Residential X X X X Hourly X X X X X E

Jain et al.(2014)

Multi familyresidential

X Hourly X X X X X E

Fan et al.(2014)

Mixed-use X X X X Next daya X X X X X X Xb Xc E

Macas et al.(2016)

Office build-ing

X 12 hours X X X X X X Xd T.H.

Mai et al.(2014)

Office build-ing

X Hourly - Daily X X X X X X Xe E, T.C.

Yang et al.(2014)

Commercial X X Annual X X X X Xf E

Paudel et al.(2014)

School X Hourly X X X X Xg T.H.

Li and Wen(2014)

Campusbuilding

X Hourly X X X X X X X E.

Juradoet al. (2015)

3 Campusbuildings

X X Hourly X X X X E.

JovanovicandZivkovic(2014)

Universitybuildings

X Daily X X Xh T.H.

Powell et al.(2014)

Campus X Hourly X X X X X Xi E, T.H., T.C.

Escriva-Escrivaet al. (2011)

Universitybuilding

X Hourly Xj Xk Xk E

Humeau(2013)

District X Hourly X X Xl E

Kapetanakiset al. (2015)

Commercial X X 15,30 minutes,hourly

X X X X X X T.H.

[a] daily peak power demand [b] profile information: mean, maximum, minimum, and standard deviation of the standardized daily time series [c] other weather variables [d] Airset point temperature; water set point temperature [e] rainfall,visibility, cloud condition, operation schedule, occupancy space power demand [f] occupancy, water temperatures, ice bankvariables [g]Occupancy profiles, operational power level characteristics, pseudo dynamic transitional attributes [h] month of the year [i] month of the year [j]maximum,minimum,average and previous day average [k] considered for the selection of the training days [l]Past consumption at different time steps

Page 5: A Data-Driven Modelling Approach for Large Scale Demand

proach based on DDM to predict monthly consump-tion, using regression approaches based on a varietyof building features.Recently, research studies showed the possibility ofcoupling DDM and parametric simulation. Chou andBui (2014),Tsanas and Xifara (2012), Catalina et al.(2008) showed that DDM are able to provide earlystage design consumption information for a largenumber of buildings. In addition, these studies un-derlined the possibility of using DDM not only as aforecasting technique but also as modelling technique.Another interesting point of the literature review pro-cess is that the most employed DDM algorithms areneural networks, support vector machines and mul-tiple linear regression. Regarding input variables,weather data and time variables are among the mostcommon, along with other information such as build-ing energy consumption. The prediction horizonvaries dependent on the nature of the application.Usually, forecasting is performed at an hourly or sub-hourly basis. The principal targets of the predictionare electric consumption and thermal requirementsboth for heating and cooling. In addition, from theliterature, it is evident that the use of DDM as anaccurate forecasting tool is limited to single build-ing applications or aggregated case studies of groupsof buildings. At district or city scale, DDM are em-ployed for single buildings predictions with an annualor monthly resolution. Recently DDM have been em-ployed as large scale modelling techniques for earlystage design power demand estimation.Hence it is evident that there are no applications andmethodologies where DDM is used as a modellingtechnique at large scale to provide accurate profil-ing information at a low time resolution. Thus, thepresent paper and the following sections present ascalable methodology associated with the use of DDMas large scale modelling technique to provide estimatebuilding power profiling information at an hourly res-olution.

MethodologyThe approach adopted in this work couples DDMwith a parametric simulation framework for provid-ing demand information of residential buildings at ahourly time resolution. The methodology is based onthe use of a representative building energy model andparametric simulation to create a database for thetraining of a DDM. The parametric simulation allowsthe creation of a virtual large scale scenario composedof similar but different buildings of the same typologyby changing building related parameters such as con-struction detail, internal gains, glazing surfaces, etc.The representative energy model could, for example,be an urban archetype representative of a large partof the building stock.Figure 1 provides a concise overview of the researchmethodology. First, a building energy model (BEM)

BEM

Energy model file description

Parametric simulator

Simulation output files

Database

Data-driven modelling

Prediction results and visualisation

MAPE RMSE

Prediction accuracy measures

BUILDING ENERGY

MODELLING

PARAMETRIC SIMULATION

APPLIED PREDICTIVE MODELLING

Figure 1: Methodology overview

of a residential building is created, i.e. the baselinemodel. A file description is then extracted from theenergy model and provided as an input to a para-metric simulator. A number of energy related inputvariables are then defined; these are applied to theBEM using the parametric simulator; as a result alarge synthetic dataset of BEMs is generated. TheseBEMs are similar but different variations of the base-line model. Outputs from the synthetic dataset, in-cluding hourly power data for both electricity andheating requirements, are then stored in a database.The DDM is then trained with the information fromthe database and prediction accuracy measures areevaluated. Based on results of prediction accuracy itis possible to evaluate the reliability of the presentedmodelling framework and to rank different DDM ap-proaches based on their predictive performance on thecase study.

Building energy model(BEM)The first step of the methodology requires the cre-ation or the use of a Building Energy Model (BEM).The case study is a mid-terraced house in Scotland.The house is part of an eco-village and part of a groupof similar buildings. The mid-terraced house consistsof two floors with a total floor area of 166m2 and a to-tal volume of approximately 359m3. The total exter-nal wall area is approximately 122m2 and the externalopenings area is approximately 29m2. A rendering of

Page 6: A Data-Driven Modelling Approach for Large Scale Demand

Figure 2: Building energy model: rendering

Table 2: Construction properties

Category U value(W/m2K)

Thickness(mm)

External Wall 0.14 359Internal Partition 1 1.79 75Ground/Exposed Floor 0.22 268Door 2.19 37Internal Ceiling/Floor 1.08 283Roof 0.09 481Internal Partition 2 0.77 226Internal Partition 3 0.14 350Roof Light 3.10 24External Window 1 1.24 24Internal Ceiling/Floor 1.10 113

the energy model is displayed in figure 2.Opaque surfaces are modelled considering roof, ceil-ing, external walls, internal partitions, ground floorand doors. Glazed surfaces include roof-lights, ex-ternal glazing and internal glazing surfaces. Table 2summarises construction properties and the thermaltransmittance assigned to the construction compo-nents.The heating system is characterised by an air sourceheat pump (air to water system) with an average sea-sonal coefficient of performance (COP) of 3.1. Theheat pump is connected to a solar heating systemwith a surface area of 2.6m2. The overall system pro-vides domestic hot water and the thermal require-ments for the building. An underfloor heating sys-tem distributes heat in the house. Electric heatersare available as auxiliary source of heat acting as asurplus, directly controlled by the occupants. Roomset points have been defined using information fromthermometers when available. Heating set point is setat 20◦C. The heating system is modelled to run con-tinuously during the period of simulation. Coolingsystems are not present in the building; if required,cooling is provided by natural ventilation in summerperiods. Occupant presence is modelled defining avalue of 22 m2/person and an occupant presence pro-file for the period of simulation. Equipment and light-ing gains are modelled considering sensor data when

available to create variation profiles and assigning apeak value in W/m2. For lighting and equipment,values in W/m2 are assigned: 2W/m2 and 34W/m2,respectively. Furthermore, the energy model is devel-oped taking into account information regarding floorplans, sections, elevations, construction, internal tem-perature sensors, flow and return temperature of heatpump, solar system and underfloor heating, flow mea-surement of heat pump, solar systems and underfloorheating, electrical meters data from lighting, groundfloor sockets, first floor sockets, heating and mainfeed.

Parametric simulationThe building simulation model is incorporated in aparametric simulation framework. Parametric sim-ulation is applied to a number of parameters whichhave significant impact on building requirements andthese include: transmittance of external walls, trans-mittance of glazing surfaces, orientation of the build-ing, infiltration rates, internal gains due to occu-pancy, lighting and equipment; the internal gains dueto occupancy, lighting and equipment are grouped to-gether and considered as a single parameter. Percent-ages of variation are applied to each of the six selectedvariables. No assumptions are made on the distri-butions of percentage of variations of the parametersand their values are decided on the basis of a range ofrealistic values for the typology of the building. Thetotal number of simulations created by the processis equal to the product of the number of variationsconsidered for each variable. Equation 1 provides themathematical description of the process:

Ns =K∏

k=1nk (1)

Ns = nK (2)

where Ns is the number of simulations, K is the totalnumber of variables, n is the number of values thevariable k can have. Equation 1 becomes equation 2if the number of values is the same for all the para-metric variables. In this study a total number k of6 variables is considered with nk = 4 variations ex-pressed as percentage of the baseline model. Table3 summarises the variables considered in this study.Four possible variations are associated to each vari-able. Therefore, with reference to equation 2 the totalamount of simulations Ns is : 4096.The parametric procedure is performed with the soft-ware IES-VE and its associated parametric simulator.The parametric simulator allows the management ofbatch simulations and to collect output data of eachsimulation. Scripting is performed in the program-ming language Lua. Thus, data is generated for 4096different simulations for a two month period (Novem-ber and December, 2014). Simulations are run with

Page 7: A Data-Driven Modelling Approach for Large Scale Demand

Table 3: Parametric simulation: variables and values

baseline units variationsU-values (external walls) 0.14 W/m2K 0.11 0.17 0.21 0.25U-values(glazing surfaces) 1.24 W/m2K 0.93 1.55 1.85 2.17Orientation - deg 90 180 270 0Infiltrations 0.15 ach 0.3 0.45 0.6 0.75Glazing surface 32.3 m2 25.5 28.7 35 38.2Internal gainsOccupancy 22 m2/person 17.6 26.4 28.6 33Lighting 2 W/m2 1.6 2.4 2.6 3Equipment / miscellaneous 34 W/m2 27.2 40.8 44.2 51

Figure 3: Predictive modelling methodology

at an hourly time step resolution. The selection of 2months of simulations is due to limit the very largeoutput dataset obtained from the parametric study.A total of 5,996,544 simulation results regarding aver-age electric demand of the building are collected andmerged together with the weather data. This datasetacts as the input to the data-analysis process for thecreation of a predictive model.

Applied predictive modellingFigure 3 shows the methodology regarding the cre-ation of the applied predictive modelling. Initially,data output of the parametric simulation (1) are or-ganised and reshaped in a data-base structure (2).The statistical software R is employed for the follow-ing steps. An initial random sample is selected fromthe overall dataset for the purpose of model trainingand model selection. In addition, randomly sampling

the dataset may artificially recreate conditions of datascarcity and sparsity: a possible condition in largescale modelling. The selected subset is of 40,000 out-put values corresponding to 40,000 different hourlysimulation outcomes (3). Three common predictivemodels found in the literature (support vector ma-chines (SVM), neural networks (NN) and generalisedlinear models (GLM)) are used for predicting aver-age hourly electric demand. Inputs to the modelsare weather variables and values of the parametricsimulations. Parameter tuning and the selection ofthe most accurate predictive model is then performedadopting a re-sampling technique, the k-fold crossvalidation method. The procedure creates k groupsof samples of equal size called folders. A model istrained using all the folders except one. Thus, themodel is used to predict values of the hold-out folderand to compute performance measures. The proce-dure is repeated several times, shuffling training andtesting folders, to perform an algorithm parametertuning procedure. In this study, a total number of 10folders is created to perform parameter tuning andbest model selection. As a result, accuracy measuresare evaluated for each model. The best model is theone that produces the minimum value of the two in-dices: mean absolute percentage error (MAPE) androot mean square error (RMSE)(4). Thus, in orderto test the effective performance of the models on anunseen dataset, another large sample (40,000 points)is selected randomly from the remaining initial data(5). MAPE and RMSE are evaluated again on the to-tal unseen dataset (6). Finally, results are visualisedin different ways to help the modeller to understandwhich model performs best (7).

ResultsPredictive models performancePredictions of the three models (SVM, NN, GLM) arecompared with the parametric simulation results toassess the capability of DDM for emulating outputs ofthe building simulation software. Figure 4 representsthe comparison between simulated and predicted out-puts. The output variable compared in Figure 4 is the

Page 8: A Data-Driven Modelling Approach for Large Scale Demand

Figure 4: Predictive modelling: simulated vs predicted outputs(Nov-Dec 2014)

Figure 5: Predictive modelling: residuals (Nov-Dec2014)

average electricity demand, averaged over 60 minutes.Another way to assess the accuracy of the predictive

models is to graph predicted and simulated data interms of residuals defined in equation 3

r = s − p (3)

where s are outputs of the parametric simulation, poutputs of the predictive models. Figure 5 shows theresults of this visualisation technique; if the oscilla-tion of the results is close to 0, it means that simula-tion and prediction data are similar. Residuals helpthe modeller to understand if the model performs par-ticularly well or not in defined situations (e.g. pre-diction capability for low or high demand values).

Next month prediction

In order to test the potential of the presented ap-proach in predicting building requirements in differ-ent scenarios, the procedure is repeated consideringonly the month of November as the training monthand the month of December for testing phase. Hence,training is performed providing, in addition to theinput explained in the methodology, the electric andheating requirements of the baseline building. Hourlyaverage electric and heating demand are the targetvariables. The results are visualised in Figure 6 andFigure 7 both in terms of predicted against simulatedresults and in terms of residuals. Thus, MAPE andRMSE are evaluated.

Page 9: A Data-Driven Modelling Approach for Large Scale Demand

Figure 6: Predictive modelling (SVM): next month prediction, simulated vs predicted outputs (total electricity)

Figure 7: Predictive modelling (SVM): next month prediction, simulated vs predicted outputs (heating)

DiscussionPrediction algorithms

Comparing the three predictive models underlines dif-ferent accuracy and prediction capabilities. From theanalysis of the predicted against simulated results itis evident that quantitatively all the algorithms per-form well. Predictions are well aligned to the diagonal

line meaning that the algorithms generalise well onthe testing set. Model comparison can be performedby the means of quality indices such as MAPE andRMSE. The RMSE ranges from 195 W, 171 W, and138 W for SVM, NN and GLM approaches, respec-tively. The MAPE values range from 5 for SVM, 7for NN and to 8.20 for GLM. As such, it is evidentthat the SVM is the model which performs best. Vi-

Page 10: A Data-Driven Modelling Approach for Large Scale Demand

sualisation of the residual between predicted and ac-tual results helps to understand if the models performwell with respect to a determined range of outcome.Both generalised linear model and neural network donot have good performances for low and high demandvalues. This is easily understandable looking at theprediction results which are averagely skewed for lowand high requirements. SVM seems to perform with aconstant accuracy on average in all the range of pos-sible outcomes. This confirms that its performanceare the best of the three models for this analysis.

Next month predictionThe previous analysis showed that SVM out performsthe other algorithms, hence, it will be deployed asthe predictive approach in this analysis. In this case,the model is required to predict unknown conditionssuch as the one generated from next month weathervariables. Output targets are average electricity andheating demand, averaged over 60 minutes for all thesimulated buildings. The results show that by in-creasing the prediction horizon and testing the pre-dictive capabilities for unknown conditions, the modelis still able to perform well with a MAPE of 6.77 forthe electricity demand and 9.57 on the heating re-quirements.

ConclusionPossible uses of the predictive modelDDM integrated within a parametric framework areable to accurately predict outputs of large sets of dif-ferent building simulations. This could lead to furtherresearch in investigating the use of DDM as a mod-elling technique in studies involving a vast number ofbuildings. A trained DDM could be employed for in-vestigating different building scenarios. For exampleit may be employed to assess the effect of changing to-tal transmittances, internal gains magnitudes, glazingsurface options, orientation, changes in building airtightness of the baseline model. Most of the variables,appropriate in retrofit analysis, may be evaluated us-ing a trained DDM. A similar approach may be as-sumed for characterising and to predict the demandof a group of buildings of the same typology of thebaseline model. The level of detail of the outcomesallows investigation at different level of aggregationcommencing with single buildings and extending toentire groups.

Advantages and limitations of the proposedapproachA trained predictive model can produce fast and re-liable results (in the range of identified errors). Thismay be beneficial in large simulation studies with sim-ilar building typologies (e.g. district or city level),where a large number of constructions affect the sim-ulation time and modelling complexity. However, theproposed approach presents a series of limitations dueto modelling assumptions that must be taken into ac-

count in order to define important improvements. Inparticular, a series of assumptions must be relaxed.Geometry is typically not homogeneous in an urbanenvironment. The heterogeneity of construction de-fines volumes, areas, adjacencies and shading effects:all of these variables highly influence modelling out-comes. Heating, cooling and electricity systems andtheir efficiencies change from building to building dueto different configuration and operations. Occupantbehaviour is highly unpredictable, it defines internalgains schedules and operation of a building, thus itis an important factor in determining the demandpattern especially in the residential sector. All theaforementioned issues must be considered for improv-ing the reliability of the presented approach. On theother hand, the scalability of the proposed techniquemay play a key role in improving its ability to repre-sent realistically an urban environment. The flexibil-ity of the parametric approach guarantees the possi-bility to increase the number of relevant parametersin the analysis and enhance the capability of DDM torepresent more realistically a large scale context.

AcknowledgementThe authors would like to acknowledge the EuropeanCommission for providing financial support duringconduct of research under FP7-PEOPLE-2013 MarieCurie Initial Training Network “Ci-NERGY” projectwith Grant Agreement Number 606851.

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