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The Naturhus Concept

A Naturhus consists of 3 parts:

the Greenhouse

the Core house
the eco-cycle system 

The greenhouse creates a Mediterranean climate around the house with fantastic outdoor spaces. The greenhouse allows for a closed local cycle of plants that absorb the nutrients in the wastewater and turn it into fruits and vegetables. A Naturhus entails a luxurious living, low energy consumption and ecology in practice. The inhabitants is surrounded by natural materials, year-round flowering roses, wine, kiwi, apricot, figs, almonds and peach. The patios around the house are used from early March to late October. The greenhouse protects humans and the core house from rain, snow and wind and the insulated house can be built more easily and with great freedom.

The vision is a sustainable building that produces food, instead of waste. A house that generates energy instead of just consuming it and introduce reflection and learning about what you eat and what you flush down the drain. What you flush down comes back to your own eco-cycle system and into the tomatoes you eat for breakfast.

A sustainable architecture that promotes a truly sustainable lifestyle. 

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Below we have gathered a description of the different parts of a naturhus:

1.    The Greenhouse
2.    The Corehouse
3.    Cycle Technology
4.    Energy and Climate

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1a. Construction:
Greenhouses can be built in many ways. The greenhouses we often work with have automa-tic ventilation along the ridge and 4 mm tempered single glazing. Tempered single glazing is above all cheaper to use than insulating glass. If you want to enclose an entire house within a greenhouse, we talk about relatively large quantities of glass. Single glazing is enough for the sun to warm the greenhouse to a comfortable 20 degrees Celcius early in the year.
The advantage of insulating glass is that the heat can stay longer in the greenhouse, there will be smaller changes in the temperature inside the greenhouse. However, it is a much more expensive solution.

The greenhouse can have a steel or a wood frame. Often, the profiles that hold the glass are aluminum. We are constantly working to ensure that all parts of the building are made of sustainable materials, which is why we advocate and develop solutions with wooden frames. Foundation of the greenhouse is done with concrete plinths + connecting foundation walls in light clinker / leca.

1b. Climate:
A great many people thrive in the Mediterranean climate. In a greenhouse positioned in a Scandinavian climate, this can be achieved much of the year with professional greenhouse technology.
You can compare it to the fact that humans thrive on the same conditions as tomatoes. Toma-toes like about 20-25 degrees warmth. If it gets too hot then both tomatoes and humans will tire. At temperatures below 14-15 degrees we want more heat, at least put on some clothes. Tomatoes want between 40-70% humidity. If it is too dry, spider mites thrive on the tomatoes and we get dry cough. If it is too humid then fungus and mold will thrive, then you can’t sell the tomatoes. Professional greenhouses dissolve problems with temperature and moisture with essential automatic ventilation and shading.
It works in the same way to live in Naturhuset. Enclosing greenhouses with automatic venti-lation via hatches in the roof, as well as shading with the help of plants, solar cells in the glass roof or textile shading solutions.

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2.THE core HOUSE 

The fully heated living-space. This is an energy efficient, compact house, built in ecological and climate-smart materials. Preferably a wood structure complemented with wood-based insulation material. Concrete, steel and oil based products (plastic) are avoided as far as possible. The rooftops and facades that are protected from wind, rain and snow can be designed and constructed with a great freedom.

The Corehouse is in a tight integration with the greenhouse spaces surrounding the inner core. This influences greatly the architectural design of the Core since the relation to the outside comes with an in-between greenhouse space.

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3.THE eco-cycle system

3a. The Eco-Cycle system (wastewater):
In order for the biological systems to survive in the long term, we cannot carry on predatory operations until everything needed for reconstruction “ends”. To talk about this, we use the Cycle Principle. We must circulate the building blocks (elements) our biological world is made of. It is particularly clear about plant nutrients (NPK). Greenhouse Livings eco-cycle system is here explained in a simplified way. The gre
ywater (shower, kitchen, laundry) and the blackwater (wc) is connected to a complete, local, small scale eco-cycle system. The wastewater is collected and treated in a series of tanks in a technical room. This is a biological process with natural bacterias breaking down the waste and turning it into nutrient water. It is then distributed out in the plant beds via a irrigation system. You get both irrigation and nutrition in one. The plants absorb the nutrients in the wastewater and turn it into fruits, vegetables and biomass. The wastewater is purified locally, a lot of water is saved and a big harvest of fresh fruit and vegetables is earned, 100% organically grown. The house does not need a connection to a municipal sewer-system.
The eco-cycle system also can be made simpler and include only the greywater. This reduces the installation cost and the size of the plant beds. This can be used in areas where the municipality demands a connection to the municipal system.

3b. Rainwater harvesting:
Lack of high quality drinking water is becoming a more and more scarce resource due to climate change. Rainwater is collected from the whole or parts of the glass roof. The gutters are connected to tanks, placed in the ground or basement. The col
lected water is stored and used for irrigation of plants, for flushing wc:s and to create outdoor ponds. This simple technology can save huge amounts of water every year.

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4. energy & climate in a naturhus

4a. General Energy-aspects in a Naturhus:
Of course, a greenhouse that covers all or part of a building provides some energy efficiency. Exactly how much is saved depends on many different factors that can be modeled in indi-vidual cases for a good estimate. However, a greenhouse around a building is not primarily aimed at reducing heating costs. A few centimeters of additional insulation and good density in a building can provide a higher energy efficiency for a building than placing a greenhouse over it - at a significantly lower cost. There are other values that motivate the greenhouse. The space outside the core house but inside the glass is a living environment where both humans and plants thrive, protected from wind and extreme cold. Roughly speaking, the greenhouse can provide an efficiency of about 30% of the annual energy use for heating.

4b. Heating system, different options:
In a well-constructed building, the heat from the people in it, the things they do and the appliances they use are the largest source of heat. It assumes that the wall, foundation, win-dows and roof are well insulated and that heat does not dissipate with the ventilation or leak through cavities.

Best indoor environment with respect to humidity, particles, organic volatile substances etc., is achieved in buildings with good air tightness and controlled supply and exhaust air in the ventilation. It enables heat exchange between exhaust and supply air and is called FTX. This type of building can be called Passive House if it meets certain criteria 

Another advantage is that systems for generating and distributing heat in buildings can be considerably cheaper and take up less space. Often, it is sufficient that the heat is distributed with the supply air, and it then becomes easy to distribute cooling on the times of the year that may be desirable. Heat is suitably generated with a small air heat pump, from waste heat remaining in the exhaust air after FTX, if it is a small building. For larger buildings, rock or ground heat can be a good alternative.

4c. Ventilation and overheating:
Ventilation is essential to regulate moisture and overheating. The nature houses function is based on professional automated ventilation systems. A standard solution in most cultivation greenhouses. Ventilation hatches along the entire greenhouse ridge are automatically opened at a certain set temperature and the overheating is effectively vented. 
Hot air rises upwards and often it is sufficient with the ridge ventilation, but when the sun gazes during the summer, shade is needed. It can be achieved with plants, shade fabric, opaque solar cells integrated in the glass roof or passive sun protection from building parts. There are many possibilities. We have also installed so-called earth pipes in some of our natural houses. The supply air to the greenhouse is led via a pipe buried in the ground, which provides a supply of cooler air in the summer and also warmer air in the winter. It is also important to be able to achieve good drafts (cross ventilation) in the greenhouse via several generous doorways in the greenhouse walls.

The geometry of the greenhouse in combination to the Corehouse is also very important to achieve a good climate and handle the potential overheating. Basically you have to make sure that you have enough height and volume in the greenhouse above the Corehouse. The top air-volume in the greenhouse holds the hottest air and there needs to be enough space here before it ventilates out.

In Sweden and the other Scandinavian countries there are a few days in the summer when overheat becomes a problem. There are far more days when the extra heat becomes a fantastic quality. That is in early spring and late autumn.

4d. Solar cells:
It is advantageous to integrate solar cells into the southside of greenhouse roofs, especially near the rooftop. They help limit overheating in greenhouses, which can otherwise be a pro-blem for both humans and plants. Traditionally, plastic films with elements of aluminum foil are used to limit solar radiation in greenhouses. However, in the large commercial cultiva-tions in the Netherlands, solar cells have begun to be integrated instead, they provide benefits in addition to reducing the excess heat.

On all surfaces of a building exposed to sun, wind and rain, it is possible to use photovoltaic modules as a surface layer. They have a long service life, have low maintenance needs (do not need to be repainted every 7 years), today do not cost much more than other surface layers if the right varieties are selected and of course generate electricity! This is called Building Integrated PhotoVoltaics (BIPV), or building-integrated solar cells.

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