Development of Aggregation Models for Building Energy Demands applied to Smart Cities

Master thesis by Panagiota Gianniou, August 2014

Abstract – The mitigation of climate change has been a priority to most countries’ agendas
nowadays. Energy and environmental policies have been introduced to facilitate the
achievement of national targets. At the same time, rapid urbanization has resulted in
converting cities into the main energy consumers and generators of GHG emissions.
Thus, they are an ideal platform where sustainable solutions can be applied which will
improve their durability and functionality. The concept of Smart Cities has the
potential to integrate sustainable technologies and innovative systems into urban
areas. At the same time, the building sector occupies a key place in the development
of Smart Cities. Energy demand of the building sector affects significantly national
energy balances. Furthermore, estimating energy demand of a cluster of buildings, a
district or city requires the aggregation of them. When handling aggregated energy
demand data, future energy predictions and the creation of what-if scenarios for
demand-side energy management are enabled. It also facilitates urban planning, as
well as the development of energy hubs into urban areas.
In the current Thesis, the theoretical background needed to study aggregation of
building energy demands is presented and analyzed. Two methods of aggregating
energy demands of buildings are identified and implemented on a real case-study,
being located in Sønderborg, Denmark. This consists of 16 single-family houses all
connected to the regional district heating system. These were modelled by Termite, a
newly-developed parametric tool, which uses Danish Be10 for energy simulating.
According to the first aggregation way, individual buildings’ energy simulations are
carried out. This method necessitates extensive data availability. Six different
information levels are investigated, concluding that apart from general data about
building’s functionality, floor area and age of construction, also information about the
most recent energy refurbishment state of the building is crucial for achieving high
accuracy in energy demand estimations. According to the second aggregation way,
building typologies are used, where five example buildings representing each type are
simulated. The results highlight that the specific example buildings represent quite
well the respective buildings, but present a deviation from the measured energy
demands. However, the annual aggregate heat demand of this method is found to be
very close to the measured one. Extensive discussion on the challenges and
uncertainties of the present city energy model is also presented.

MSc Thesis_Panagiota Gianniou_s121414.

Panagiote Gianniou is today a PhD at DTU Byg. You find her work at http://orbit.dtu.dk/en/persons/panagiota-gianniou%285d72c44b-00d7-4f6f-b174-b34d9f337a20%29.html.

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Modellering af den termiske masse i bygninger med det formål at bestemme bygningers evne til at flytte energiforbruget i tiden

Bachelor thesis by Frederik Lynge Holvorsen, June 2015 (Danish)

(English: Modelling of thermal mass of buildings, aiming at flexibility, demand shifting of energy demand for heating and cooling.)

Introduktion (Danish): Den øgede anvendelse af vedvarende energi medfører store udfordringer med at holde
energisystemerne stabile. Da det før kun var forbrugssiden, der svingede, er det med vedvarende
energikilder, også produktionssiden der viser udsving. Dette kan medføre uhensigtsmæssige
ekstremsituationer, som kan være ”spidser” (peaks) eller ”huller”. Derfor
arbejdes der på teknologier, der er i stand til at flytte energiforbrug i tiden, for eksempel
ved at lagre energi. I bygninger er det oplagt at udnytte bygningens masse hertil. Der er
dog ret stor usikkerhed omkring den mængde energi, der kan lagres, når for eksempel
overskydende elektricitet fra vindmøller kun er til rådighed i korte perioder. Nærværende
projekt vil, gennem modellering undersøge, hvordan varmetransporten og varmelagring
foregår i typiske konstruktioner og materialer. Dermed er der mulighed for at estimere potentialet
for fleksibilitet som bygninger kan tilbyde det omgivende energisystem.

Produktionen af bæredygtig energi og energibehov er ikke nødvendigvis sammenfaldende
rent tidsmæssigt. Dette gør sig gældende med hensyn til udnyttelse af vindenergi, som bidrager
til en større og større del af Danmarks energiproduktion. Vindmøller kan f.eks. producerer
strøm om natten hvor behovet for energi i boliger og kontorer er lavt.
Det er derfor relevant at afdække mulighederne for at kunne lagre overskydende energi til
senere brug.

1.2 Formål
Formålet med dette bachelorprojekt er at undersøge bygningers evne til at flytte varmeforbruget
i tiden gennem termisk lagring i bygningsmassen. Denne undersøgelse sker ved
hjælp af matematisk modellering af den termiske masse.

1.3 Fremgangsmåde
Projektforløbet blev delt op i tre faser. I den første fase opstilles og analyseres de nødvendige
teorier, som danner grundlag for at undersøge muligheden for at forskyde energiforbruget
i bygninger.

Abstract (English):

Background: Huge challenges occur with an increasing use of sustainable energy. Some
of these challenges are associated with securing the stability of the energy systems and to
continuously meet consumer energy demand.

Objective: The objective of this project is to provide knowledge regarding the ability to
store thermal energy in buildings and increase the load shift potential, by implementing
mathematical models to support analytics and decision-making. This project will examine
how heat transfer and heat storage is done in typical structures and materials to help estimate
the potential for flexibility which buildings can offer the surrounding energy systems.

Method: This paper is based on a combination of a recognised theoretical foundation,
which forms the basis for exploring the possibility of shifting energy consumption in buildings.
The theory is used to prepare two models in Ida Ice and Comsol in order to verify the
accuracy of Ida Ice. The theoretical foundation and the setup of the models are revisited
and adjusted in an iterative process, in order to obtain the same performance in Ida Ice as
in Comsol and verify the use of Ida Ice.

A range of experiments have been designed in order to simulate different thermal situations
in order to demonstrate the flexibility potential of buildings.

Results: The verification of the building simulation program Ida Ice shows a discrepancy
when comparing to the theoretical foundation and formulas implemented in Comsol. It will
require further investigations to identify the underlying reason of these observations.

The results of the experiments show that it is possible to store energy in order to make use
of this at a later time. However this requires a longer preheating period and the time period
where the energy demand can be shifted is limited.

Bachelorprojekt, Frederik Halvorsen s123095 (final).

Proposal: EnergyLab Nordhavn – Huge opportunity for Tech Nerds

The EnergyLab Nordhavn is is investing min. 150 mill. DDK into a living lab of tech solutions that aim at solving the sustainable future city challenge. There are project opportunities en mass – If you are looking for a tech project, here you have the opportunity to make a difference. The investments into hardware, internet communication, data storage, buildings, components are made – you can concentrate on doing the tech development, research, innovation.

There are projects for sustainability, energy, building automation, software development, modelling and simulation, planing, monitoring en hardware, data management, data science and much, much more … What would you like the future city to give you – here we may have the opportunity to test it.

For non-tech nerds – there are opportunities for user-related research, economical studies, anthropological studies, you may even make some architectural-cultural studies … – We work together with the relevant research institution to make this realistic.

The project can be found online at: http://www.energylabnordhavn.dk/

Contact (Al)Fred Heller.