building hot water models for urban and regional energy integration alex bertrand riad aggoune...
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BUILDING HOT WATER MODELS FOR URBAN AND REGIONAL
ENERGY INTEGRATION
ALEX BERTRANDRIAD AGGOUNE
FRANÇOIS MARÉCHALBIWAES 2015, STOCKHOLM
- Urban and regional energy integration approaches based on Mixed Integer Linear and Non-Linear Programming (MILP, MINLP) for the definition of energy optimisation scenario
- Optimised parameters: operating and investment costs, energy consumption, emissions
- Urban projects focus on building energy demand: space heating and cooling, electricity, hot water consumption
* Weber C., 2008, Multi-objective design and optimization of district energy systems including polygeneration energy conversion technologies, Thesis, EPFL, Lausanne, Switzerland
CONTEXT
- Use of simplified hot water demand models: constant demand during the day (70 l/day*capita), instead of peak demand
Energy integration outcomes for the city of Geneva (CH)*
- Determination and characterisation of hot water streams (end-uses) in different residential and non-residential buildings (offices, hospitals, hotels restaurants and swimming pools) : temperature levels, load, availability rate and number of appliances ([Blokker et al. (2010)], [Pieterse-Quirijns et al. (2010)], [Blokker et al. (2011)], [Pieterse-Quirijns et al. (2013)] )
- Definition of an aggregation factor, the simultaneity factor, for buildings with several households or units (e.g. rooms in hospitals)
- Comparison of simplified and detailed load models for hot water applied to the city of Esch-Alzette (Luxembourg)
APPROACH
HOT WATER MODELS
- Input: inlet and outlet temperatures Tin (10°C) and Tout, minimum temperature difference at heat exchange dTmin (5K), thermal power
End use types
HOT WATER MODELS
- Hot water load at household level:
Phw = 1,15 Pn,I max- Buildings with several households / units:
- Simultaneity factor:
- Hot water load :
Building and district aggregation
Assumptions: 70 l/d*capita, 60/10°C, 5:00-23:00, households
CASE STUDY – SIMPLIFIED MODEL
CASE STUDY – DETAILED MODEL
DISCUSSION
- The hot water power requirements in single-family house using the detailed model is between 6 to 135 times higher than with the simplified model
The detailed models show a large range of values, due to the consideration of various hot water end-uses and not the number of inhabitants
- The use of a simultaneity factor for utility sizing leads to a load reduction of 83 % for buildings with more than 50 inhabitants
- The thermal load of well-insulated buildings is mostly defined by hot water demand, while offices are not affected much as space heating is more relevant in terms of power requirements
CONCLUSIONS
- The use of detailed hot water models will provide more realistic investment cost estimations
- The utility selection following the energy integration approach will lead to different technology solutions.
- Geographical clustering methods used for district heat network design could profit from simultaneity factors to reduce district load requirements
- The application of a randomizing function distributing various end-use types better reflects the stochastic equipment distribution
- Next Steps: inclusion of use patterns for multi-time problems, application of hot water models for national energy integration approach including both building and industrial hot and cold streams
