Foto: Frontansicht des Biohofs Achleitner

e80^3-Buildings - Sub project 2: Concept development

Based on the selection of suitable demonstration projects in Subproject 1 an innovative concept for passive and active building envelopes and energy supply of so called "Plus Energy Buildings" (renovation) has been developed.

Short Description

This project is a subproject of the flagship project "e80^3-Buildings - Renovation Concepts for Residential Buildings to Plus-Energy Buildings with Prefabricated Active Roof-and Façade Modules, Integrated Building Services and Grid Integration"




Starting point / motivation

Compared with newly constructed buildings, in retrofit the conditions of the existing building have to be particularly regarded and the focus has to be on the reduction of the energy consumption of the building. Therefore the aim is the improvement of the thermal quality of the building envelope and the implementation of an innovative energy production and energy supply system.

The improvement of the thermal quality includes the reduction of the thermal losses (transmission and ventilation) and the consideration of the necessary measures, which are based on an in-depth investigation. So the thermal envelope has to be optimized regarding the geometry, heat losses and thermal bridges. This will be done by different studies.

At the same time the requirements of an optimized solar energy production (solar thermal and photovoltaic) have to be considered as well: a comparison of different measures should deliver the advantages and disadvantages of each solution. With this information the decision will be eased.

Objectives and contents

The objectives and aims of the sub-project 2 "development of concepts" in the regarded report period are:

  • Additional in-depth investigation of the actual state of the demonstration-project*
  • Definition of target values and requirements for plus-energy-retrofits (target state)
  • Target/actual analysis of the demonstration-project
  • Optimized retrofit-concepts for the thermal envelope to achieve a min. 80% reduction of the heating demand of the demonstration-project
  • Development of an innovative energy supply concept to reach the plus-energy-standard with grid integration

Methods of treatment

Sub-project 2 was divided into six work-packages. In each work-package different methodical approaches were used:

WP 1 - In-depth investigation

The in-depth investigation was carried out with the relevant project partners and supplemented by necessary measurements.

WP 2 - Definition of the objectives and requirements; deduction of the retrofit-strategy

The main focus in WP2 was the comparison of the target and actual state. Thereof the specific measures for the building and retrofit works were deducted.

WP 3 - Conception of the thermal envelope

The aim is the development of a retrofit-concept for the thermal envelope to reduce the heating demand of the demonstration-project by min. 80%.

WP 4 - Conception of the energy supply system

The objective of WP4 is the development of an innovative energy supply concept to reach the plus-energy-standard with grid integration.

WP5 - monitoring and evaluation concept

In WP 5 an overall concept for net-integrated plus-energy-buildings will be created. Additionally the main concept for the monitoring and evaluation of the demonstration projects will be deduced. This includes also an ongoing agreement with the methodology of the evaluation within the framework of the Building of Tomorrow Plus - key projects.

WP6 - efficiency analysis

The aim of WP6 is the research and the determination of the basis of assessment for the life-cycle-costs and the environmental quality of the demonstration projects and the assessment of the chosen energy supply system.


Sub-project 2 should, based on the choice of the appropriate demonstration-project in sub-project 1, develop an innovative concept for the active and passive building envelope and the energy supply system for plus-energy-buildings in retrofit. The realignment of the building to an intelligent energy producer in heat and electricity grids not only includes the minimisation of the losses and the maximisation of the energy gains but rather also the optimal integration into the heat and electricity grids and the utilization of synergies in the direct vicinity. Innovative concepts optimize the heat and electricity supply from the energetic perspective and also in the way of running the cables by integration into the building envelope.

The objective is to obtain a concept (for each demonstration-project) for the retrofit to a plus-energy-building out of a progressively development process. This development process represents the basis for the further realization of the whole key-project.


Project Partners

Project management

DI Dr. Karl Höfler
AEE - Institut für nachhaltige Technologien

Project collaborator

DI Sonja Geier, DI Armin Knotzer, DI David Venus

Project- and cooperation partners

Contact Address

AEE - Institut für nachhaltige Technologien
DI Dr. Karl Höfler
A-8200 Gleisdorf, Feldgasse 19
Tel.: +43 (3112) 5886 25
Fax: +43 (3112) 5886 25-18

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