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Our team

Management Team

Dr. Birgit Memminger-Rieve

Managing Director & Partner
Birgit studied Environmental Engineering at Stuttgart University, and in 2006 she gained her PhD at its VEGAS research centre. Since 2007, she has dedicated herself to the sustainable management of real estate and is recognised throughout Europe as a leading expert in building certification and ESG consulting. Birgit is also an experienced auditor for Green Building rating systems such as LEED® and BREEAM and sustainable portfolio assessments (GRESB). Birgit is originally from Stuttgart, but she now lives with her family by the beautiful Lake Tegel in Berlin.
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Frank Burchardi

Managing Director & Partner

Frank is our co-Founder and Managing Director. He founded the business in 2001 with Birgit. Frank studied geology at the Heidelberg and Kiel Universities. His professional career began at the Salzgitter Elektronik AG in Kiel. In 1990 he changed companies and became project manager at wave GmbH in Stuttgart with focus on contaminated sites investigation and clean-up. Frank has more than 30 years of professional experience. During the last 20 years he has been consulting international clients in the due diligence sector (real estate acquisition and sale). He is married and lives on the northern coast of Germany.

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Ingemar Hunold

Authorised Signatory & Partner
Ingemar is one of our Partners. He joined EnviroSustain in February 2016 and heads up our Frankfurt office. As one of our all-rounders, Ingemar works on a huge variety of projects with a focus on strategic sustainability consulting. He advises our clients on the development and implementation of sustainability strategies for international real estate portfolios. This includes ESG training as well as ESG reporting and leading our ESG data management. Before joining EnviroSustain, Ingemar worked for Union Investment for three years as project manager in sustainable real estate. He studied architecture and climate design in Munich and Chicago.
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Main Team

Business functions

Stefanie Klinge-Davis

Employee Relations Manager
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Miriam Daniel

Finance Assistant
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Sam Wheeler

Marketing Director
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Olaf Anhalt

Acquisition Manager
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Directors

Nicole Isking

Director
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Aurélie Simon

Director
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Oliver Bach

Director
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Jan Herde

Director Innovation & Tools
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Gilbert Sonntag

Director
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Project Directors

Wioletta Simlat

Project Director
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Vanessa O'Brien

Project Director
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Luise Keiderling

Project Director
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Florian Fahle

Project Director
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Daniel Josties

Project Director
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Claus Zeller

Project Director
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Víctor Núñez Navarro

Project Director
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Senior Consultants

Kay Christine Ahlers

Senior Consultant
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Marie-Lou Roederer

Senior Consultant
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Christina Mildner

Senior Consultant
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Meike Ringering

Senior Consultant
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Andrew Davis

Senior Consultant
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Sudheep Senthilkumar

Senior Consultant
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Christian Seifert

Senior Consultant
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Junior Consultants

Archana Arivoli

Junior Consultant
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Erik Haugbak

Junior Consultant
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Finn Frambach

Junior Consultant
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Working Students

Abigail Watson

Working Student
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Jacob Wójtowicz

Working Student
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Contractors

Avery & Brown

Brand and Marketing Partners
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Dr. Hossein Sagheby

Consultant
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Pauline Kortmann

Photographer / Videographer
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Saskia Uppenkamp

Photographer / Videographer
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Working at Es
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Who we are
What we do
How it is with us

Head Office Berlin
Neue Grünstraße 17/18
10179 Berlin
Germany

Office in Kassel
Loßbergstraße 20
34130 Kassel
Germany

Photography is by Saskia Uppenkamp

We plant trees with Ecologi
© 2024 ES Enviro Sustain GmbH

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Website by Avery & Brown

Stefanie Klinge-Davis

Stefanie joined EnviroSustain in July 2019 after 18 years of living and working in the UK. She studied Arts Management at the University of Leeds and previously worked in a variety of roles, including Marketing, Customer Relations and Event Management. At EnviroSustain she is the link between the organisation, staff and management, aiming to continuously improve the staff experience remotely and in the Berlin office. This also includes organising regular team events, in Berlin and further afield. With a particular interest in organisational culture, Stefanie enjoys creating a positive working environment for all.
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Miriam Daniel

Miriam joined ES in June 2021 straight after parental leave. As a Finance Assistant she is responsible for accounting. Before joining ES, she worked for several years at a tax consultancy in Berlin where she also completed her training. Before discovering her passion for numbers, Miriam trained as an IT systems administrator and worked for several years for a German cable network operator. Together with her family, Miriam lives in the green Berlin district of Spandau and she is delighted to be able to support ES.
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Sam Wheeler

Sam joined us in January 2020 as Marketing Director, based in the UK. Sam oversees the development of our entire marketing function. This includes taking responsibility for the organisation’s branding and design work, as well as our online presence, internal communications, public relations and event management. She studied Business Studies and Marketing at university and has over 15 years’ experience in crafting multi-channel campaigns, brand management and graphic design. Much of her time has been spent working for various not-for-profit organisations and consultancies in the construction and sustainability industries. Sam lives in Kent with her husband and four rescue animals.
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Olaf Anhalt

Olaf’s relationship with EnviroSustain began back in 2005, when he was the Technical Director at Land America – one of EnviroSustain’s early clients. Olaf has a broad range of experience, and he is a well-rounded professional. His previous roles have included project management, reinsurance, and business development. As EnviroSustain’s Acquisition Manager, Olaf is responsible for introducing us to new prospects. He lives with his family in Munich and also works at Munich RE’s office.
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Nicole Isking

Nicole studied environmental engineering at the University of Stuttgart and joined EnviroSustain in October 2010 as a Project Director. As one of our most experienced LEED®- and BREEAM Project Directors, she serves our clients in the areas of new construction, modernisation and existing buildings. She is also part of our ESG team and performs ESG assessments at the asset and portfolio level. Ms. Isking lives with her family at Lake Constance and enjoys nature in her free time.
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Aurélie Simon

Aurélie joined our team in April 2019 and is one of our directors in the Berlin office. Her work focuses on project and team management in the areas of Technical Due Diligence, LEED® certification and energy consulting (including decarbonisation studies). As a native French speaker, Aurélie also provides valuable support for our projects in French-speaking countries. She spent part of her career as an energy efficiency consultant in France and China. She has been living and working in Germany since 2013. Aurélie is trained in building services engineering and energy technology.

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Oliver Bach

Oliver studied Environmental Process Engineering at HTW Berlin. He has been working with us since March 2010 and is one of our most experienced consultants in our Berlin head office. He oversees ESG monitoring for project developments and prepares decarbonization strategies on portfolio and asset level as well as decarbonization audits and Green CapEx for selected properties. As an experienced LEED®, BREEAM, WiredScore and SmartScore project manager, Oliver serves our clients in the areas of new construction, refurbishment and existing buildings. He also brings many years of experience in GRESB assessments and performs them for international real estate portfolios. Oliver lives with his wife and three children in the countryside outside of Berlin.
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Jan Herde

Jan joined ES at the end of 2013 as a Senior Consultant and Architect in our Frankfurt office. Jan is an all-rounder who works on a wide range of projects in energy and sustainability consulting. He is also one of our three DGNB auditors. The focus of his work includes ESG and decarbonisation audits, thermal building simulations, energy efficiency concepts and the development and application of ESG assessment tools. Prior to joining EnviroSustain, Jan had his own business working as an energy consultant and DGNB auditor.
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Gilbert Sonntag

Gilbert joined our team in the summer of 2007 as our first English-speaking civil engineer and has been working in the Frankfurt area for over 15 years. He is an extremely experienced project manager who works for our clients in both technical and sustainability areas. As a building expert (well over 250 Technical Due Diligence projects), project monitoring manager (supervising numerous construction projects through to handover to the client), energy consultant (well over 1,000 energy performance certificates issued), BREEAM auditor and assessor (supporting more than 250 existing building certifications throughout Europe), DGNB auditor for new and existing buildings (advising major clients on ESG issues), GRESB expert (various portfolio evaluations), etc., Gilbert is delighted that there is always an exciting selection of projects to work on. He is an honorary city councillor and an active member of the volunteer fire brigade in his hometown; he is married and has three children; his hobbies include travelling and photography.

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Wioletta Simlat

Wioletta joined EnviroSustain in March 2021 as Project Director in the Berlin office. She is an experienced project manager and trained in architecture and civil engineering with a degree in “Climate Friendly Construction and Operation” from Brandenburg University of Technology. As a LEED BD+C Accredited Professional (AP), she primarily coordinates LEED new construction projects and supports the ESG team with her expertise as needed. She is also a certified ECARF building consultant and advises our clients on allergy-friendly building design. And as WELL AP, Wioletta is our expert in design practices supporting Health and Wellbeing of the building occupants. In her spare time, she enjoys being creative – crocheting, knitting, sewing, baking cakes!
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Vanessa O'Brien

Vanessa O’Brien (born Schröder) has a master in quality and sustainability management and has been part of the ESG team since 2021. Her responsibilities include building assessments as part of ESG due diligence or ESG checks as well as reporting to GRESB. She is also an expert for the DGNB system ‘Buildings in Operation’, but also works in the certification of new construction and refurbishment projects. She is also active in ESG strategy consulting and is happy to answer questions about taxonomy and disclosure regulations (SFDR). She lives in Berlin with her family.
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Luise Keiderling

Luise has been working as a Project Director in our Berlin head office since the beginning of 2021. She is part of our ESG team and contributes in particular to sustainability strategies and reporting topics, and leads some GRESB projects. As a trained BREEAM DE Inventory Auditor, she coordinates and works on many BREEAM projects in Germany. Mrs Keiderling is also a trained ESG manager (DGNB). Luise has completed a Master’s degree in Business Ethics and CSR Management at the Technical University of Dresden and is also a trained environmental management officer according to ISO 14001.
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Florian Fahle

Florian is a state-certified technician for heating, air conditioning and ventilation technology and has 14 years of professional experience. Before joining ES in June 2021, he was employed for 13 years in a planning office for building services engineering, most recently as project manager for major projects in the Rhine-Main region. Within his professional career, Florian has also taken on planning and property monitoring activities and now supports the ES team in the areas of technical due diligence, decarbonisation studies, project monitoring and commissioning management. Florian Fahle lives with his family in the countryside 60 km west of Kassel.
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Daniel Josties

Daniel has worked with ES since the beginning of 2022 as a consultant on ESG topics and sustainability in the building sector. He has extensive professional experience as a creative designer, organiser and technician, and also has experience as a lighting planner. After completing his professional training as an event technician in Leipzig, he obtained his master’s degree in interior architecture at the BURG Giebichenstein KHS Halle. He attributes his desire to contribute to a more sustainable building industry to, among other things, his concern for the future of his two children. Together with his family, he lives north of Kassel in Göttingen.

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Claus Zeller

Claus joined EnviroSustain in 2005 in our Stuttgart office. He is one of our Project Directors. In 2017 he moved with his family and now is part of our Frankfurt team. Claus delivers a variety of services, but focuses predominantly on technical and environmental due diligence projects and project monitoring. Before joining us, Claus had his own business and worked as a geologist involved with building contamination and sub-soil contamination projects.

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Víctor Núñez Navarro

Víctor completed his architecture degree (M.Sc.) in sunny Alicante, Spain, and has 8 years of work experience in various fields, including building construction, industry, and retail. He is a certified DGNB auditor and ESG manager, roles that enable him to ensure sustainability and responsible management in real estate projects. Currently, he is studying Industrial Real Estate Management at the University of Stuttgart, further expanding his knowledge and skills in this specialized field. Víctor lives in Cologne, a city he greatly enjoys, especially during the carnival season, when the streets are filled with life and colour.
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Kay Christine Ahlers

Kay has been with us since 2011 and is one of our Senior Consultants. She focuses on LEED® projects for existing buildings and new constructions, particularly in the field of sustainable and low-emitting materials as well as waste management. She is also part of the ESG team.

After qualifying as a construction draughtswoman, Kay studied chemical engineering at Münster University of Applied Sciences.

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Marie-Lou Roederer

Marie-Lou joined our Berlin office as a consultant in 2019 with a background in architecture. She works mainly on technical due diligence and monitoring projects but is also part of our ESG team and has successfully completed her training as a BREEAM DE auditor. Her mother tongue is French, which brings in many benefits for our projects in Belgium and France.
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Christina Mildner

Christina Mildner has been working as a Senior Consultant for ES at the Kassel office since mid-2022. She supports the ESG team with regard to corporate strategies, the GRESB portfolio assessment system and is gaining initial experience with BREEAM. A legal background, a Master of Law, a degree in corporate environmental protection and sustainability management as well as many years of experience in dealing with authorities are useful, but in her opinion, a successful transformation ultimately depends very much on the attitude of those involved. She would like to help ensure that the change takes place primarily in people’s minds (and hearts).
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Meike Ringering

Meike joined the EnviroSustain team in Kassel at the beginning of 2023. She focuses on BREEAM, GRESB and DGNB projects and is therefore closely involved in the assessment of real estate (new builds/existing buildings) in terms of sustainability. She also focuses on ESG regulatory, management and reporting issues, and supports knowledge transfer within the company and ESG training for our clients.

Meike holds a bachelor’s degree in economics (B.Sc.) with a focus on environment and sustainability and a master’s degree in sustainable management (M.Sc.). During her studies, she acquired comprehensive knowledge of environmental, climate protection and construction law, among other things. With her dedicated work, Meike contributes significantly to the achievement of the company’s goals.

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Andrew Davis

Andrew joined the company’s Berlin Office as a Senior Consultant in July 2019, coming from the UK with a background in Environmental Emission testing. At university he studied Environmental Management and Sustainable Waste Management and now enjoys living and working in Germany. His focus is on working on our LEED® and GRESB projects as well as conducting ESG audits.
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Sudheep Senthilkumar

Sudheep comes from Chennai, a coastal city in southern India, and joined ES Berlin office in July 2023. He completed his Master’s degree in Energy and Environmental Engineering at TU Berlin. Building on his educational background, he gained practical experience as a project manager specializing in facility and energy services. His focus is on the topic of LEED® certifications and GRESB projects. He is motivated by the opportunity to contribute to creating a better world for all.
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Christian Seifert

Christian joined EnviroSustain in the Berlin office in February 2023 as a Senior Consultant with a focus on ESG Due Diligence, decarbonisation audits, as well as EPCs and BRREAM certification for existing buildings. He has a dual degree in Supply and Environmental Engineering from the University of Cooperative Education in Glauchau and a master’s degree in Sustainable Building Design from the Berlin University of Applied Sciences (BHT). He has work experience in manufacturing, the real estate sector and energy/neighbourhood planning, as well as practical construction site experience.

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Archana Arivoli

Archana joined EnviroSustain in Berlin in February 2025 and works with the LEED®, BREEAM and DGNB teams as well as supporting the team issuing EPCs. She is also working on life cycle analyses. She holds a bachelor’s degree in architecture and an MBA in Building Sustainability from TU Berlin. She began her career working in architecture firms in India and is intrigued by the idea of blending eco-friendly practices with innovative design while maintaining architectural integrity. A nature lover by heart, Archana enjoys spending time outdoors, drawing inspiration from the natural world and continues to explore innovative approaches to create sustainable and resilient communities.

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Erik Haugbak

Erik has been working at EnviroSustain since October 2024 as a Junior Consultant at the Berlin office, specializing in ESG consulting and certifications. He completed his studies in Mechanical Engineering (BSc) and Sustainable Energy Systems (MSc) in Gothenburg (Sweden) and gathered 2.5 years of experience in the real estate industry living and working in Stockholm. Erik now lives in Berlin and is passionate about driving the industry and society towards more climate-smart and sustainable solutions and looks forward to contributing to a greener future.

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Finn Frambach

Finn Frambach has been working as a junior consultant at the Berlin office since January 2025, having previously been part of the team as a student trainee. At EnviroSustain, his work includes ESG assessments of buildings and developing measures to improve energy efficiency and reduce CO₂ emissions.

Finn studied building energy technology in Bremerhaven and obtained a master’s degree in industrial engineering from the Berlin University of Applied Sciences. He is excited to further develop his knowledge in the field of sustainable construction as part of the consulting team and to apply it in a wide range of projects.

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Abigail Watson

Abigail Watson has been working at EnviroSustain since January 2023, mainly in the area of LEED certification. She is American and has lived in Germany since 2018. She is currently studying Technical Environmental Protection (Bachelor) at the Technical University of Berlin. She is looking forward to putting her knowledge gained at university into practice and to further expanding it at ES.

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Jacob Wojtowicz

Jacob joined the EnviroSustain team in May 2025 and focuses primarily on BREEAM certifications. He is German with Polish roots and is currently studying Technical Environmental Protection (Bachelor’s degree) at the Technical University of Berlin. At ES, he is excited to apply what he has learned in his studies in a practical setting while gaining new insights.

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Avery & Brown

Brand and Marketing Partners

Avery and Brown are trusted partners to purpose-driven businesses that want to put sustainability at the heart of their growth. We provide a tailored four-step process to help you: understand your audience, competition and priorities; define your brand and position in the market; solve specific problems you currently face; and execute that research into actionable change.

We are also working on #OperationRegeneration: our mission to become a regenerative business – one which gives back far more to society and the planet than it takes.

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Dr. Hossein Sagheby

Hossein joined us in May 2017. He mainly works at the University of Applied Sciences HTW Berlin as Professor for Building Energy and Information Technology. Hossein is an expert in the field of building technologies, and he focuses mainly on delivering our energy efficiency projects.
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Pauline Kortmann

Photographer / Videographer

Pauline supports EnviroSustain with her camera since spring 2022 as a freelance photographer and videographer. After training as a media designer, she studied animation at the Film University Potsdam-Babelsberg, where she explored the topic of climate change in her award-winning diploma film, an animated children’s documentary. Since then, she has worked on various projects on sustainability as a director, writer and animator.

Paulinekortmannphoto.de

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Saskia Uppenkamp

Photographer

Since 2014, Saskia has been working as a freelance photographer in the areas of portraiture and reportage. Always on the lookout for stories, portraying artists or photographing reports on sustainable topics. Alternative concepts of living interest her in a special way. Saskia also works in the field of corporate photography and observes people with her camera at big events. Her pictures have been published in ‘The Wall Street Journal’ and ‘Lufthansa Magazin’, among others.
www.saskia-uppenkamp.com

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