Automated Generation of an Energy Simulation Model for an Existing Building from UAV Imagery

Philip Gorzalka,Bernhard Hoffschmidt,Christian Schorn,Jacob Estevam Schmiedt

doi:10.3390/buildings11090380

Philip Gorzalka, Bernhard Hoffschmidt + Show 2 more

Open Access

https://doi.org/10.3390/buildings11090380

Copy DOI

Journal: Buildings	Publication Date: Aug 26, 2021
Citations: 7	License type: CC BY 4.0

Affiliation: German Aerospace Center, FH Aachen

Abstract

An approach to automatically generate a dynamic energy simulation model in Modelica for a single existing building is presented. It aims at collecting data about the status quo in the preparation of energy retrofits with low effort and costs. The proposed method starts from a polygon model of the outer building envelope obtained from photogrammetrically generated point clouds. The open-source tools TEASER and AixLib are used for data enrichment and model generation. A case study was conducted on a single-family house. The resulting model can accurately reproduce the internal air temperatures during synthetical heating up and cooling down. Modelled and measured whole building heat transfer coefficients (HTC) agree within a 12% range. A sensitivity analysis emphasises the importance of accurate window characterisations and justifies the use of a very simplified interior geometry. Uncertainties arising from the use of archetype U-values are estimated by comparing different typologies, with best- and worst-case estimates showing differences in pre-retrofit heat demand of about ±20% to the average; however, as the assumptions made are permitted by some national standards, the method is already close to practical applicability and opens up a path to quickly estimate possible financial and energy savings after refurbishment.

Highlights

The buildings sector is directly or indirectly responsible for 18.4% of total anthropogenic greenhouse gas emissions [1]
The goal of this study is to demonstrate how largely automatable processes starting from UAV-based remote sensing can be used to generate a building energy simulation model
After the model is augmented by additional simple pieces of information about the house acquired from owners or inhabitants, it is enriched with energetically relevant properties and processed to a Modelica simulation model using the open-source tools TEASER [33] and AixLib [35]

Summary

Introduction

The buildings sector is directly or indirectly responsible for 18.4% of total anthropogenic greenhouse gas emissions [1] Reducing this impact is one of the key issues for mitigating global warming. For a pathway that aims at limiting global warming to an average temperature increase of 1.5 °C, existing buildings should be renovated at a rate of 5% per year by 2020 [2]. These include minimum requirements for energy retrofits of existing buildings and rules for their execution. As the first step of renovation measures, the laws usually demand an analysis of the current state, e.g., by energy consultants. They evaluate the status quo energy performance according to national or international standards and give recommendations for suitable retrofit measures. For the post-retrofit state, requirements regarding overall energy demand, thermal transmittance (U-values) of certain building parts, or whole building heat transfer coefficients (HTC) apply [4]

Objectives

Methods

Results

Conclusion