G2Plus makes your energy efficient

More expertise for more efficiency

G2Plus stands for the two G’s of GASAG and Gegenbauer, strong companies that unite their expertise and experiences. And the partnership shows that both companies are ready to provide services and individual customer solutions that point the way to the future. G2Plus was initiated as a joint venture in September 2016 and has already successfully completed a diverse range of projects. GASAG and Gegenbauer are a pair of companies that come with expertise and extensive experience, long-standing tradition and economic strength. Both are backed up by glowing references from a large network of customers in the energy industry and facility management sector. GASAG and Gegenbauer guarantee a reliable pool of experienced and professional advisors and engineers. As a result, G2Plus offers comprehensive interdisciplinary expertise that is well-established in the fields of energy and facility management.


Our goal is to make your properties as energy efficient as possible in order to reduce costs and protect our environment. Profitability, sustainability and statutory provisions are requirements that we help you meet. G2Plus achieves this by using the two companies’ latest methods and cutting-edge technologies, as well as those of specialised partner enterprises.

Our experts for more energy efficient


G2Plus is a team of experienced experts. We draw on a large pool of expertise from GASAG and Gegenbauer that enables us to offer customised, perfect-fit solutions. This unique network also includes recognised specialist engineers from other companies.

André Wolff


Mr Wolff has over 20 years of experience in managing major projects in the field of technical building equipment. As the head of plant engineering at one of the largest technical building services companies in Germany, he managed a technical planning office as well as a highly effective building department. Mirroring the lifecyle of a building in his professional career, he then devoted himself to the area of facility management as a branch manager at a large FM service provider. There, he provided training to the energy management/energy efficiency area. Under his leadership, an energy management system according to DIN EN 50001 was launched at a service company with over 15,000 employees. Mr Elstermann has been the sole managing director of G2Plus since February 2019.


Jennifer Horn

Team Assistant

After completing her secondary education, Ms Horn began a training course as an office administrator at the Gegenbauer Group that also included a focus on the Gegenbauer Facility Management division. Ms Horn was then immediately employed as a management assistant at Gegenbauer. She has been continuously training in the commercial and business services areas since that time. As a team assistant at G2Plus, she also provides support for advisory activities in the field of energy services.

Andreas Frost

Project Manager for Energy Services/Auditor (BAFA)

Mr Frost began his career as a mechanic for the maintenance of machine tools. He then completed a degree as a graduate engineer in mechanical engineering in the metal processing industry. Following his studies, he worked as a process engineer, IT project engineer and sales engineer in the manufacturing industry. A switch to consulting led to an ongoing specialisation in the direction of energy management. Among other roles, Mr Frost worked as a project manager in a Federal Ministry of Economics and Technology (BMWI) funding programme for Berlin-Brandenburg on the topic of ‘Energy Transition for SMEs’. Mr Frost has supported G2Plus since its founding as an energy consultant for SMEs and as an auditor (Federal Export Office) for DIN EN 16247-1.

Mario Kähne

Project Manager for Energy Services

Mr Kähne started his professional career as an industrial electrician. His further training at the Chamber of Crafts in Frankfurt (Oder) as a master mechanical engineer served as the basis for managing larger projects including, for example, object monitoring in accordance with HOAI (Fee Structure for Architects and Engineers) Service Phase 8 in public buildings and hospitals or the introduction of automation technology for recording system states, the drafting of control strategies as well as automatic invoicing for the customer. Mr Kähne became qualified in the area of switching equipment for operating and handling electrical systems using 1 kV to 30 kV in the course of further training at TÜV Süd, where he also obtained certification as a person in charge of fire alarm systems according to DIN 14675. He has supported the team at G2Plus as a project engineer for energy efficiency consulting and the implementation of energy services measures since mid-2017.

Jessica Schönebeck

Marketing and Project Manager for Energy Efficiency

Ms Schönebeck, a certified real estate agent, began her career at a housing association in Hamburg. She completed a bachelor’s degree with a technical focus in the area of facility management at the Münster University of Applied Sciences in cooperation with Beiersdorf AG in Hamburg. Following a semester abroad in Helsinki, Finland as part of an English-language master’s programme at the HTW Berlin – University of Applied Sciences, she was employed in the real estate services area at an international FM service provider in Dublin, Ireland. She then joined Gegenbauer Facility Management in Berlin and worked closely together with Gegenbauer and G2Plus to successfully complete her master’s in digitisation and Industry 4.0 in the area of energy and facility management. Ms Schönebeck has worked as a marketing and project manager for energy efficiency at G2Plus since summer 2017.

Sebastian Villain

Project Manager for Energy Efficiency

To acquire a seamless transition to working life following his degree course in process and environmental technologies at the Beuth University of Applied Sciences, Mr Villain initially worked alongside his studies as a student trainee at a publicly listed automobile and engineering company. He joined the team at G2Plus GmbH for the practical component of his degree course and to support the completion of his thesis. Since his successful graduation Mr Villain works as a project manager for energy efficiency at G2Plus.

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