Development of a new Building Energy Model in TEB Bruno Bueno Supervisor: Grégoire Pigeon

19/10/20092 Contents  Introduction  Previous work  Simplified BEM  Model evaluation  Conclusions Acronyms used in this presentation: BEM – Building Energy Model HVAC – Heating, Ventilation, Air Conditioning system

19/10/20093 Introduction  Introduction  Previous work  Simplified BEM  Model evaluation  Conclusions

19/10/20094 Introduction General goal  Combine the knowledge accumulated in building energy and urban climate studies to investigate the interactions between buildings and the urban environment and to develop a new BEM integrated into TEB.

19/10/20095 Introduction Building representation in urban climate studies  TEB does not include a comprehensive BEM to calculate building energy consumption and waste heat emissions.  This has already been solved in other urban canopy models (Kikegawa et al. 2003, Salamanca et al. 2010).  These models still present important limitations in terms of active and passive building system models, which are important to develop UHI mitigation strategies and to calculate HVAC waste heat emissions.  In the last month, a new simplified BEM has also been implemented in TEB, showing a good performance. Kikegawa et al. 2003

19/10/20096 Previous work  Introduction  Previous work  Simplified BEM  Model evaluation  Conclusions

19/10/20097 Previous work The TEB - EnergyPlus Coupled Scheme BUILDING ENERGY MODEL URBAN CLIMATE MODEL Air temperature Air humidity Wind speed Wall temperature Conv. coefficient HVAC waste heat

19/10/20098 Previous work Comparison Coupled Scheme vs. TEB  On the left, the Coupled Scheme is able to reproduce the results obtained with the original version of TEB, if a simplified building model is defined in EnergyPlus.  On the right, the Coupled Scheme includes a detailed definition of a typical office building and the calculation of waste heat emissions.  Annual simulations made for a hot climate (Abu Dhabi) Bueno et al (submitted to BLM)

19/10/20099 Previous work Case study: Effect of waste heat released into the canyon –Annual simulations made for a hot climate (Abu Dhabi) Fraction of waste heat released into the canyon Annual consumption anomaly associated to the UHI effect f =0%-2% f =50%5% f =100%10%

19/10/ Previous work Case study: Effect of adding an economizer to the HVAC system –Annual simulations made for a hot climate (Abu Dhabi) Annual consumption error associated to the UHI effect in the presence of economizers: 15%  An economizer allows more ventilation outdoor air than the minimum to enter the HVAC system when outdoor conditions are favorable (Tout < Tin).  This takes advantage of the cooling energy of outdoor air (if available) and reduces the energy consumption of the HVAC system.

19/10/ Simplified BEM  Introduction  Previous work  Simplified BEM  Preliminary results  Conclusions

19/10/ Simplified BEM  A new simplified BEM has been developed and implemented in TEB.  The simplified BEM accounts for:  Sensible internal heat gains.  Solar transmission through windows.  Heat storage of building thermal mass (floors and ceilings).  Steady state heat conduction through windows.  Infiltration/ventilation energy load.  Dynamic evolution of indoor air between a cooling and a heating thermal setpoint.  The new BEM can estimate building energy loads, HVAC energy consumption, and HVAC waste heat emissions.

19/10/ Simplified BEM Assumptions of the simplified BEM with respect to detailed building simulation programs:  The building is represented as a single thermal zone with a generic internal mass.  Constant internal gains.  Constant infiltration air flow rate.  Ideal HVAC system.  Solar heat transmitted through windows does not depend of the incidence angle of the sun. All solar heat transmitted is perfectly absorbed by the internal mass.  Convective/radiative approximation for the heat transfer from indoor surfaces.  The effect of windows and infiltration is not yet included in the outdoor energy balance.  The latent component of the heat exchanges is not considered.

19/10/ Model evaluation  Introduction  Previous work  Simplified BEM  Model evaluation  Conclusions

19/10/ Model evaluation Experimental campaign CAPITOUL. Toulouse; Feb, 2004 – Feb, ACH – Air Changes per Hour COP - Coefficient of Performance

19/10/ Model evaluation Comparison among the new simplified BEM, the Coupled Scheme, the previous TEB, and the experimental data set CAPITOUL. Simulation parameters: Building height20 mInternal gains5 W/m2 Building density0.68Infiltration rate0.7 ACH Wall to horizontal ratio1.05Indoor thermal set-points19ºC – 27ºC Wall construction Brick 30 cm Fraction of waste heat released from walls 0.5 Internal mass construction Concrete 20 cm COP of the cooling system2.5 Glazing ratio0.3Efficiency of the heating system0.9 Fraction of electric heating systems 0.5 ACH – Air Changes per Hour COP - Coefficient of Performance

19/10/ Model evaluation Building energy performance – Coupled Scheme vs. BEM Indoor air temperature Ten days in intermediate period (01/ /10)

19/10/ Model evaluation Building energy performance – Coupled Scheme vs. BEM Cooling energy consumption Ten days in cooling period (01/ /08)

19/10/ Model evaluation Building energy performance – Coupled Scheme vs. BEM Heating energy consumption Ten days in heating period (01/ /11)

19/10/ Model evaluation Building energy performance – Coupled Scheme vs. BEM HVAC waste heat emissions Ten days in cooling period (01/ /08)

19/10/ Model evaluation Outdoor energy balance – CS vs. BEM vs. TEB vs. Observations Wall temperatures Ten days in cooling period (15/ /07)

19/10/ Model evaluation Outdoor energy balance – CS vs. BEM vs. TEB vs. Observations Road temperatures Ten days in cooling period (15/ /07)

19/10/ Model evaluation Outdoor energy balance – BEM vs. TEB vs. Observations Roof temperatures Ten days in cooling period (15/ /07)

19/10/ Model evaluation Outdoor energy balance – BEM vs. TEB vs. Observations Sensible heat fluxes Ten days in cooling period (15/ /07)

19/10/ Model evaluation Outdoor energy balance – BEM vs. TEB vs. Observations Net radiation heat fluxes Ten days in cooling period (15/ /07)

19/10/ Model evaluation Outdoor energy balance – Coupled vs. BEM vs. Observations Anthropogenic heat fluxes Ten days in cooling period (15/07 – 25/07) Ten days in heating period (05/ /02)

19/10/ Model evaluation Outdoor energy balance – Coupled vs. BEM vs. Observations Electric energy consumption Ten days in cooling period (15/ /07)

19/10/ Model evaluation Outdoor energy balance – Coupled vs. BEM vs. Observations Gas energy consumption Ten days in heating period (05/ /02)

19/10/ Conclusions  Introduction  Previous work  Simplified BEM  Model evaluation  Conclusions

19/10/ Conclusions  A new simplified BEM has been successfully developed and implemented in TEB.  The model is able to estimate building energy loads, HVAC energy consumption, and HVAC waste heat emissions.  The TEB–EnergyPlus Coupled Scheme is a useful tool to evaluate current and future developments of BEM.  Next steps include the analysis of some parts of the outdoor surface energy balance implemented in TEB and in EnergyPlus.

19/10/ Conclusions  Future developments of BEM will include a better description of windows, as well as a selection of active and passive building systems.  To test which active and passive building systems should be implemented in TEB for the purposes of this project, we need a set of typical buildings, characteristic of French cities.

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