Award-Winning New City Hall of Freiburg: The World's 1st Public Net-Plus Energy Building

The New City Hall in the City of Freiburg is a highly energy efficient public building that has received national awards and international recognition. The municipal building, which was completed in 2017, is an example of how local government commitment and vision, the effective collaboration of specialist firms and a careful balancing act between economic considerations and environmental sustainability ambitions can result in a modern and future-proof administrative building. In addition to benefits such as lower maintenance and running costs, the working environment of local government staff has improved and citizens benefit from the concentration of administrative functions and services in one central location.

Constructed over a 33-month period and costing 82.5 million Euro, the 24,215 m² building provides office space for 840 local government employees. The distinctive curved design features a highly insulated building envelope with integrated photovoltaic panels (PV), an expansive array of rooftop PV and hybrid panels. Heating and cooling are achieved via a ground-water coupled heat pump system and groundwater heat exchanger.

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The Mixed-Use HIKARI Complex: A Successful International Collaboration Delivers Positive Energy

Completed in 2015, the HIKARI buildings are one of the first large scale mixed-use positive energy building (PEB) complex in Europe. The buildings proved the viability of ambitious energy targets by combining cutting edge energy generation, saving and storage technologies and benefiting from consumption peaks of the various uses controlled by an innovative building energy management system.

The HIKARI complex is located on the most emblematic site of the new Confluence District, a mixed-use development site that brings together commercial, residential and leisure functions in the South West of the centre of the French City of Lyon. Located at the corner of the Charlemagne course and overlooking the new Place Nautique, the complex is in the centre of a vibrant new urban development area that was conceived as a “smart city” prototype.

HIKARI is a great collaboration example, harnessing public-private synergies between France and Japan. The partnership provided the necessary governmental, technological and financial conditions to form a multidisciplinary team of urban planners, architects, engineers, builders and managers.

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Lantti-talo: Designed for High Replicability for Detached, Terraced and Low-Rise Apartment Buildings

Lantti-talo (Lantti House) is Finland's first net zero energy single family house, which actually went over the limit of net zero demand, exporting more energy than importing. It demonstrates that it was possible to achieve the 2020 energy efficiency targets already ahead of time. The project contributed to the development of energy efficient building design and construction, recognising the future development needs in Finnish climatic conditions. The project produced information about the importance of city planning for the optimal positioning of building, PV-panels and solar collectors and for the achievement of high energy efficiency.

The goal was to use as many renewable and carbon dioxide -storing building materials as possible and simultaneously aim for energy savings. Design solutions were evaluated with sensitivity analysis. The energy consumption of the different building options was assessed with simulations in the design phase. As a result, Lantti is an overall eco-efficient house with an airtight and well-insulated structure. Eventually, the result was a plus energy house, as it produces considerably more electricity than it needs with photovoltaic panels and gets part of the heating from solar collectors.

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SOLACE HOUSE - the First Prefabricated Plus Energy House

SOLACE House is an invention of the Polish start-up with the same name and aims to challenge prevailing paradigms in the housing market. Offering an alternative, this future-oriented home is affordable, durable, modern looking, carbon-neutral and energy-positive.

Designed to reduce energy consumption, with solar panels fixed on its tilted roof, it produces more energy than it needs and sells surplus energy to the grid, thus keeping the living and maintenance costs to a minimum. The house is made up of 16 prefabricated parts that are delivered to the customer in only one container and can be easily assembled in less than 72 hours. It is claimed to be “the first prefabricated plus-energy house”.

The first SOLACE House was erected in Warsaw. The realization of the other houses, commissioned by customers across Poland, is on the way.

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Solarhaus Building: Reaching New Heights with a Planned Residential PEB in Spain

SOLARHAUS, which is to be built in Pamplona, Spain, and is scheduled to be completed in 2021, will be one of the first residential Positive Energy Buildings (PEB) in the country. The unique high-end design is the result of a successful collaboration between architectural practice, science and a forward-looking client.

The building design successfully balances architectural aesthetics, functionality and energy performance, thereby proving that PEBs in Spain are both technically possible as well as commercially viable. The building will feature a powerful rooftop photovoltaics installation, four air-water heat pumps, a highly insulated building envelope, radiant flooring for heating and heat recovery ventilation.

In light of a recent Spanish decree on energy self-consumption, which greatly facilitates the installation of renewable energy generation technology, projects such as SOLARHAUS have significant potential for replication in the country. Moreover, the project could be readily reproduced in many other countries with similar regional policies, private initiatives and market´s inclination to solar projects.

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The TU Wien (Vienna University of Technology): Award-Winning Plus-Energy Retrofit of a High-Rise Office Building

The Plus-Energy Office High-Rise Building of the TU Wien (Vienna University of Technology), completed in 2014, is the first example of a sustainable renovation of an office tower building, which generates more energy than it consumes. It is also a great example of successful interdisciplinary collaboration, simultaneous, integrated planning, as well as a well-developed usage concept.

In addition to drastically reduced energy consumption (by up to 88%), the building produces electricity directly through a photovoltaic system integrated into the facade and mounted on the roof and via energy recovery from the elevator. Energy recovered from the server’s waste heat is the main source of heating for the building.

This building proves that renovation with a plus-energy concept is not only technically possible but also commercially feasible.

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The Aerem Factory: An Ecological Co-Designed Factory Building

The Aerem building in the South of France proves that also factories, which typically have a relative high carbon footprint, can reach positive energy standards. The building was constructed in 2018 and uses a modular steel structure as a basis which can be adapted and extended to adapt the factory for varying future uses.

The steel structure is insulated with locally harvested straw to further reduce the carbon footprint of the construction materials. The combination of steel and straw, used in an industrial context, is one of the key innovations in this project. Heating and cooling are provided by a geothermal heat pump system in combination with (high flow) night ventilation. Electricity is generated by photovoltaic panels on the roof.

The building was designed in close collaboration with its future occupants in order to understand and meet up with their functional needs. Special attention was paid to acoustic comfort, air quality and visual aspects to increase occupants’ satisfaction and well-being. The Aerem factory has won the low Carbon Prize of the Green Solutions Awards both in France and internationally.

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NEWTONPROJEKT Collective Housing: a Role-Model for Residential Positive Energy Buildings

Realised in 2018, the NEWTONPROJEKT in Berlin can be seen as a great model for the future of residential positive energy building (PEB) construction in Germany and elsewhere. Benefiting from attractive financing options for energy efficient buildings and applying a collective user-centric approach to property development, the building ensemble delivers not only more energy than it consumes but incorporates a host of environmental considerations.

NEWTONPROJEKT House 1, which is the focus of the case study, uses renewable and recyclable materials where feasible and its residents benefit from adaptable, accessible and comfortable apartment units. Moreover, sustainable mobility solutions have been incorporated in the design and the collaborative planning approach has created a stronger sense of community. A key success factor underpinning this project was the partnership with the local district heating network operator. Not only is renewably generated electricity exported to the grid during times of surplus, but also solar thermal heat can be fed back into the network. Such an integrated approach would greatly enhance the replication potential and broader adoption of PEBs in Germany and beyond.

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Passivistas: Transforming a 1960's residential building in Papagos, Greece

TheHouseProject demonstrates that even in economically difficult times retrofitting existing residential buildings so that they generate more energy than they consume is both financially and technically feasible.

Bringing together a team of experts and finding support from private sector partners as well as via crowdfunding, renovation works were carried out in 2015 and 2016 using materials and technologies available on the market. The cost for transforming the 125 m² two-level structure into a positive energy building (PEB) will be amortised in under seven years by energy savings.

The Passivistas team has made a great contribution to raising awareness and building capacities for PEBs with over 1,000 visitors taking part in open house events and seminars. Whilst the project already has great replication potential in Greece and beyond, scaling up the energy efficient renovation of residential buildings could be catalyzed further by tailored financial solutions, more ambitious regulations, and incentive schemes.

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