building hot water models for urban and regional energy integration alex bertrand riad aggoune...

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

THANK YOU FOR YOUR ATTENTION

ANY QUESTIONS?

alexandre.bertrand@list.lu