PlusEnergy is a coined concept developed by Rolf Disch that indicates a structure’s extreme energy efficiency so that it holds a positive energy balance, actually producing more energy than it uses. With the completion of his private residence, the Heliotrope, in 1994, Disch had created the first PlusEnergy house in the world. The sheer logic of a home that creates more energy than it consumes made perfect sense to Disch. His next goal for its development was the mass application of the concept to residential, commercial and retail space. As the concept further developed and gained financial backing as well, Disch built several more projects with the PlusEnergy concept. PlusEnergy is a simple concept that has been materialized in a technical design. “PlusEnergy is a fundamental environmental imperative,” Disch claims. PlusEnergy is more than just a new energy standard, but it is also an integrated ecological and architectural concept.
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To reach its positive energy balance PlusEnergy harnesses a variety of techniques to both minimize energy use and maximize renewable energy generation. For example, the large North and South facing window areas in the PlusEnergy design allow maximal amounts of natural sunlight to penetrate the structure. This eliminates the need for energy use from light bulbs during the day while it simultaneously captures warmth. The triple-paned windows (U-value = 0.7) trap heat inside, allowing more heat to enter the structure than to exit. With the addition of the highly efficient insulation, the structure is then already warm in the evening and therefore needs less heating. In the Sun Ship, a 60,000 sq ft (5,600 m2). commercial, retail and residential PlusEnergy structure, such cutting edge building technology as phase changing material in the walls and vacuum insulation are used. This permits maximum availability and utilization of floor space without compromising efficient insulation. The solar technology of PlusEnergy buildings are made aesthetically pleasing so that they are integrated into the façade of the structure. Furthermore the solar technology is made affordable, especially in respect to maintenance and repair. Also essential to the PlusEnergy concept is community planning and integration. Disch believes PlusEnergy must include solutions also for transportation, water management and social communicative function. These are equally imperative as energy solutions and are the reasons the PlusEnergy concept is more than just a new energy standard. An important difference between the passive and the PlusEnergy standards is that PlusEnergy allows the owner or tenant of a PlusEnergy building to live and work comfortably with normal energy output and without lifestyle sacrifices. PlusEnergy is built exclusively with sustainable natural building materials and stands strides in front of the passive standard because of its positive energy balance.
Built originally in 1994 as the private residence and special project of Rolf Disch, the Heliotrope is a one-of-a-kind design. The Heliotrope in Freiburg was the first building in the world to create more energy than it uses, of which is entirely renewable, emissions free and CO2 neutral. The structure physically rotates to track the sun, which allows it to harness the maximum natural sunlight and warmth possible from the sun. Several different energy generation modules are used in the building including a 603 sq ft (56.0 m2) dual-axis solar photovoltaic tracking panel, a geothermal heat exchanger, a combined heat and power unit (CHP) and solar-thermal balcony railing to provide heat and warm water. These innovations in combination with the superior insulation of the residence allow the Heliotrope to produce anywhere between four to six times its energy usage depending on the time of year. The Heliotrope is also fitted with a grey-water cleansing system and built-in natural waste composting. After the success of Freiburg’s Heliotrope, Hansgrohe contracted Rolf Disch Solar Architecture to design and built another Heliotrope to be used as a visitor’s center and showroom in Offenburg, Germany. A third Heliotrope was then contracted and built in Hilpoltstein, Bavaria to be used as a technical dental laboratory. Disch’s unique design accommodates different utilization from private residences to laboratories, all the while maintaining the structure’s positive energy balance. In addition to the original Heliotrope design, Rolf Disch Solar Architecture has drawn plans for larger versions of the project to be built as rotating hotels, which give every guest a beautiful view, as well as administrative buildings and even an exhibition pavilion for the EXPO 2010 in Shanghai.
With the success of the Heliotrope, Rolf Disch Solar Architecture wanted to apply their PlusEnergy concept to mass residential production. The new design for the PlusEnergy house gave way to the development of the Solar Settlement, a 50 PlusEnergy home housing community. This residential complex won such awards as 2002 House of the Year, 2002 residential PV solar integration award, 2006 Germany’s most beautiful housing community. It is the first housing community in the world in which all the homes produce a positive energy balance and which is emissions-free and CO2 neutral. Built between 2000 and 2005 in the Vauban quarter of Freiburg, the Solar Settlement has proved Disch’s vision of a “fundamental environmental imperative” as these homes have exhibited more than 8 years of full occupancy and each produced more than 5,000 Euros ($5,600) each year. The design of each home offers maximum energy efficiency and turns energy bills into energy income. Rolf Disch Solar Architecture considers the image such a community exhibits is equally as important as the eco-savings it brings. The tenants at the Solar Settlement do not claim to have made any compromises in their living situations but rather that they have both environmentally and economically improved. Made from Black Forest timber, the wood interior and natural lighting provide for happily lit spaces and a natural flow from room to room.
Rolf Disch Solar Architecture then morphed the PlusEnergy design concept into a large integrated office/retail building. The Sun Ship, located directly next to the Solar Settlement in Freiburg, uses its 60,000 sq ft (5,600 m2). for retail, commercial and residential space. The Sun Ship houses a supermarket, convenience store and bakery-café on the first floor, offices and work spaces on the 2-4 floors and 9 penthouses on its roof. As a whole, this building produces more energy than it consumes per year and utilizes the most up-to-date building technology. Some aspects that make this building particularly unique are its vacuum insulated walls, ventilation with 95% heat recovery, triple paned windows and its energy façade. As the first positive energy office building worldwide, the Sun Ship exhibits not only extreme efficiency but also a warm environment to work in. The office spaces are flanked on both the North and South ends entirely with windows, which maximizes natural sunlight, employee views and minimizes the energy wasted by artificial light. In addition to the office and retail space, two conference rooms, one large and one small, provide space for lectures, meetings and as a showroom.
Community planning goes hand in hand with sustainable development and thus Rolf Disch Solar Architecture dedicates much if their design and planning to the symbiosis of their projects surroundings. A solar community generates identification and an enormous public image. Disch says he attracts great tenants, innovative undertakings and creative work places through his design. Rolf Disch Solar Architecture always aims to create a community with combined uses for an ecological urban planning concept like traffic management – with wide, attractive walkways, bike routes and connections to public transportation. At the Solar Settlement for example, tenants and owners incorporate bike- and carsharing and the neighborhood has an extensive car-free zone with many public transportation connections. Rolf Disch Solar Architecture also has incorporated community solutions for energy. For example, a biomass cogeneration unit is extremely expedient, which meets the (reduced) additional heating demands for his Plusenergy homes.
2008 German Sustainability Award
2005 Wuppertal Energy and Environment Prize
2003 Global Energy Award
2002 European Solar Prize
2001 Photovoltaic Architecture Prize Baden-Württemberg
Solar Settlement and Sun Ship Video
Rolf Disch Solar Architecture
PlusEnergy