Architectural design

Floor plan of the large stone house

The large stone ground floor house of 45.2 sq.m. is developed in plan L and consists of a living room, a kitchen, two bedrooms and a bathroom. On the north east side of the house, the bright living area with the built-in open kitchen have unobstructed view of the sea and the natural landscape. To the south, adjacent to the living room, the south pergola delivers a covered patio, which hosts the open air dining area. The two bedrooms and a bathroom are located on the west side of the house. The master bedroom opens to a second outdoor terrace covered with a seed trellis on the south side of the house. This second open-plan seating area is formed of the exterior stone wall that protects the buildings from the strong north winds. 

Big stone house plans

Sun path diagrams with shadow ranges throughout the year

During the design process of the two houses, the Tinos Ecolodge team used sun simulation programs on the plot in order to better understand the impact of the sun in relation to their project and its surrounding context. The sun path is a visual representation of the sun’s range movement across the sky at the specific geographic location of their project, on the outskirts of Tinos Island. Four specific months have been chosen to show the sun path and the shadow area changing process, January, April, June and August.

Annual sun path and shadow range of the small stone house through the year

Calculation of daylight factor levels

Variant: North window moved to west corner. two skylights 60X60 cm, one on the bedroom and one on the livingroom. Time:14.:00

The daylight levels inside the houses where simulated in the design process, that helped position the windows and skylights to the desired positions in order to archive optimal lighting condions. The daylight factor is the most commonly used performance indicator for the evaluation and specification of daylight conditions in buildings. It evaluates the amount and distribution of diffuse light in the building in relation to the amount of diffuse light available outside under cloudy sky conditions, and is expressed as a percentage. Daylight factor levels are determined on a plan view and at 3D sections.

Construction progress 

(clockwise from left) Foundation of the small stone house. Basic infrastructure is placed in the foundation such as wastewater, fresh water and electricity.  (next image) Construction process of cistern. The cistern required to store the rainwater throughout the summer. Cistern 240sqm of hard surface collects around 100,000L of rainwater for 6-8 people and for irrigating the gardens. (last image) Concrete slab that form the ground floor of the small stone house.

Construction process of the big stone house. Empty pipes are directly installed in the floors and walls so electricity wiring is prepared and it is now invisible on the finished wall.

(clockwise from left) The stone masons worked in teams of 2, one on the outside wall and the other on the inside. The stone wall has a thickness of 50 cm . Between the outer and inner sides of the wall, there is a filling of smaller untreated stones and mortar.(next image) Stone masonry started at the small house. 30% of the stones are extracted from the plot excavation and used in building the walls. The rest came from a local quarry. (last image) Placed single irregular stones lintels across the top of the doors and windows.

Construction process of wooden ceiling which is insulated with 5cm Dow insulation (Extruded polystyrene insulation/ XPS). The concrete slab was poured/ cast over the insulation layer.

(left image) Applying cement mortar on the terraces and on the inner floor of the houses and. Warm, earthy cementitious colors were chosen for lining floors (interior and exterior), terraces and built-in furniture in the kitchen and bathroom. (right image) Construction of a masonry kitchen counter-top.

(clockwise from left) The frames were made from custom-made local carpenter. In the large wooden windows, German mechanisms were installed to close the openings as tightly as possible. The frames were placed in the middle of the stone wall in order to limit the sunlight you absorb from the wooden frame and better protection from rainwater. Double energy glass panels were placed by filling the gap with argon gas and a low-emission coating (Low-e). (next two images) Construction process of the wooden pergola with reeds. Reed shading provides relief from harsh rays while still allowing for a cooling breeze to pass through.

We like to thank Nick Bedau for the information,
photos and plans he provided us. More articles
about Tinos Ecolodge and their expansion will be coming soon.

Back to part No1 >

Tinos Ecolodge is far away from centralised networks for power, water, waste and waste water. These circumstances combined with the owners’ philosophy for a better, ecological, economical and sustainable solution, has resulted in the selection, design and implementation of off-grid infrastructures. As a result, these lodges achieve maximum comfort with as little energy as possible and with a low environmental footprint.

On the east side of the beautiful Greek island of Tinos, just before the beautiful beach of Santa Margarita, lies Tinos Ecolodge a ecofriendly tourist destination. These lodges promise to get people out of their daily routines, offer relaxasion and healthy living in touch with nature. The wild forested with oak trees agricultural plot offers a stream with big plane trees and riverside vegetation which makes this place very green and wild. The view to the sea in front and to the islands of Mykonos and Ikaria completes the picture and the magnificence of nature at its best.

The arrangement of the two residences on the sloping plot offers magnificent and panoramic views
of the landscape and Aegean sea.

The two stone-built lodges are perfectly integrated into the natural environment, inspired by the traditional houses of Greek islands and build with natural stone and wood as the material of choice. However, the materials of these traditional buildings have been reinterpreted creating a thermally efficient contemporary architecture, combining functionality and finesse. Also the exploitation of the extraordinary potential of the plot in terms of orientation, slope and view was a basic pursuit of the design of the dwellings. 

Sustainable design

The following solutions are implemented in Tinos Ecolodge:

• use of renewable energy resources, photovoltaic system and wind generators, to product electric power
• rain water collection and storage in a 100,000L cistern
• waste water treatment
• composting human manure
• use of treated waste water for non-edible plants and trees
• filter the waste water by Reed-bed system for sewage treatment and reuse for garden irrigation
• natural light design and solar thermal design
• use of high quality wooden frames and energy glazing
• natural ventilation
• shading the yards with reeds
• built completely out of local stone, from local stone masons using the traditional technique that has been preserved on Tinos

Two stone houses

The large house of 45.2 sq.m. is developed in “L” floor plan and the small one with an area of 31.4 sq.m. in rectangular floor plan. The two houses are completely independent, separated by the utility house in the middle terrace and with different orientation, preserving their privacy. Each house consist of an open-plan living room adjacent to kitchen space, a bathroom and two bedrooms in the big house and one in the small one. The kitchen opens to the big terrace in front of the house with garden, built-in sofa and dining table. The exterior stone walls protect the buildings from the strong north winds of the island while forming these gorgeous small terraces – outdoor seating areas.

The installation of windows is mainly to the south and the east for the purpose of natural light and ventilation, while creating visual escapes to the sea, the Acratos and the Cycladic islands. The design of the two houses allows users to enjoy the most of the sun, natural light and view.

Interior design

The interior is comfortable and bright. The carefully curating of the minimalist with traditional touch interior design combines functionality, comfort and high aesthetic, creating a cozy atmosphere. The furniture, floors and paintings are custom made.
The stone surfaces remain visible in-house, while the floors are covered with cast cement mortar in light orange color. The high thermal mass of stone wall combined with wooden frames (windows & doors) results in steady indoor temperature at a relatively constant intermediate level of about 18 ° C.

The minimal style of the master bedroom in combination with the exposed natural stone wall creates a serene and tranquil space that’s perfect for relaxing.

(clockwise from left) The kitchen cabinets are built into plastered countertops. At the left side of the exterior stone wall is a two recess which are used to create storage compartments.
(next image) Rustic wooden open closet in the master bedroom.
(last image) An old wooden window turned into a bathroom mirror.

Thanks to the natural stone features (high heat capacity) and the high thermal mass of the 50 cm thick exterior walls, the houses are well protected from the natural elements and the thermal comfort is maintained throughout the year.

External environment

The relationship between the building and the external environment is particularly important. The garden and the buildings are complementary connected. The two houses are well integrated into the natural environment, because of the layout of the buildings and the courtyards on the contour line (altitude lines) of the hill, the continuity of the natural environment remains unbreakable. The use of local building materials (stone, wood, reeds) combined with the free growth of vegetation on the plot create a sense of continuity of the natural with the built environment.

Tinos-Ecolodge team:

Marilia Kalouli: She studied Rural resources and environmental policy and she worked for environmental projects in many areas, with the aim of promoting ecotourism and conservation. Nowadays, Marilia directs Tinos Ecolodge in partnership with Nicolaos Bedau.  
Nicolas Bedau: He studied Landscape architecture and he works in the field of environmental design and education, while he is the administrator of Tinos Ecolodge.
Ronan Lewis: He works freelance in the rope access industry as a technician and builder.
Rafael Krause: He studied Landscape architecture and he works as an educator with teenagers. 

Continue reading >

This simple and graceful new residence fulfills the Passive House standard  and is a high quality living space with low operation costs thanks to a combination of superb detailing in the design process and the fabric first building design.

Moreover, X-G group aimed to minimize the need for energy consumption through methods such as:

• Maximum thicknesses of insulation requirements
• Thermal bridge free construction
• Careful airtightness detailing
• Optimizing solar gain through the provision of openings and shading
• Using the thermal mass of the envelope
• Non-implementation of projections on the walls of a building or overhangs
• Reducing as far as possible the exposure of the building envelope to the elements of nature by adding adjacent non-heated auxiliary spaces
• Using the energy from occupants, electronic devices, cookers and so on

Design-wise, the finished result is a beautiful, bright, modern minimal 299 m2 house which manages to achieve superb energy efficiency. Moreover, the three bedroom home efficiently delivers spoils such as excellent indoor air quality, thermal comfort and low energy bills.

Architecture design

The house consists of four autonomous volumes that interlink, forming a courtyard at the south side of the property.

The main volume consist of an open-plan living adjacent to kitchen space, a master bedroom with a private bathroom, a guest room and a small WC on the ground floor. A metal staircase with wood cladding leads to two bedrooms and a bathroom in the upper floor.

On the southern side the second volume of the residence contains the parking and storage space. This ingeniously built-in storage space adjacent to the Passive House enhances the thermal resistance of the housing envelope.

The third volume on the west side is designed and constructed as a solar space. Due to its orientation, its south glass facade facing the courtyard maximizes the houses passive solar heating. The glass surfaces can seal in the winter improving the energy performance of the building. In summer, the solar space is protected against radiation via a motorized roller blinds system.

The fourth volume on the east is a semi-open construction housing the main entrance of the residence. It protects the housing envelope from the elements of nature.

Mechanical Systems

The living space is divided into four thermal zones, each one with temperature control capability, so that different space-conditioning requirements, heating and cooling set point / temperatures can be selected in each space.

The building’s main space heating system consists of a heat generation GAS condensing boiler. The space heating is provided by three towel radiators, 700 calories each, which are installed one in each bath. Internal walls between baths and bedrooms transfer small amounts of heat required in the bedrooms while at the same time ensuring a 2 °C higher temperature in the baths, a requirement imposed by international thermal comfort standards.

In the kitchen the thermal energy released from electrical appliances (for lighting and cooking) suffices for space heating. It is also protected from the solar heat. In the basement the thermal energy dissipated by the fixed mechanical equipment is also sufficient for space heating.

Ventilation system with heat recovery, ensuring that the indoor air is constantly replaced with fresh air, while saving significant amounts of energy. The special features of the system (Bypass, subsoil heat exchanger “air-soil” by REHAU eff. specif. HRE: 82%) contribute to the maintenance of thermal comfort,  while allowing the system to provide, beside fresh air, significant amounts of heating in the winter and cooling in the summer.

To ensure cooling during the summer months, air conditioners were installed, one on each floor.

Additionally, a key installation is the motorized roller blinds system that allows or prevents the entry of solar radiation as you please without preventing the natural light and the view from the yard.

Hot water is supplied via a GAS condensing boiler and a thermal solar collector with surface area: 5,2m² (DHW distribution in circulation pipes). The solar panels are located on the roof of the building and the hot water tank in the basement.

(clockwise from top left) Installation of EPS (033) from 200mm to 350mm insulated foundation system to provide continuous insulation thereby reducing heat flow and improving energy efficiency. (next image) Reinforced concrete slabs form the basement and ground floor of the building, insulated above with EPS (033) from 150mm to 200mm and poured lightweight concrete 40mm. The foundation walls and concrete slabs have damp proofing membrane applied to the exterior insulation to prevent damaging wetness and moisture from seeping in through the walls but also help to rid the house of residual moisture. (next image) Masonry construction. (next 2 images) Applying EPS (033) from 200mm to 350mm on the external walls of the building. (last image) A wet plaster finish is used for the airtight layer of the walls. Plaster is inherently airtight, as is concrete. Plaster finish is used in a masonry construction to create a continuous and effective airtight layer. Also in the picture metal battens forming a ceiling service cavity through which the rigid MVHR ductwork runs. A good airtight seal around pipes where they pass through the external wall.

Selected Project Details

Architecture design: Stefan Thomas Chatzoulis / XG group of engineers

Statics: Christine Georgiadi / XG group of engineers

Main contractor: Stefan Thomas Chatzoulis / XG group of engineers

Buildings physics: Stefan Thomas Chatzoulis / XG group of engineers

Detailing: Stefan Thomas Chatzoulis / XG group of engineers

Photo: © George Goutzoulias / Light Box

In Detail

Building type: 299,24 sqm detached single family house

Location: Volos, Magnesia, Greece

Completion date: 2017

Annual heating energy demand: 11 KWh/m²y

Heating load = 13 W/m²

Annual cooling energy demand: 13 KWh/m²y

Cooling load = 9 W/m²

Primary energy requirement: 66 kWh /(m²a ) on heating installation, domestic hot water, household electricity and auxiliary electricity calculated according to PHPP

Airtightness (@ 50 Pascals pressure): 0,54/h air changes per hour 

Exterior walls: brick 90mm, EPS (033) from 200mm to 350mm. Uwall = 0,126 W/(m²K)

Roof: reinforced concrete 150mm, EPS (033) 300mm. Uceiling = 0,116 W/(m²K)

Basement floor / floor slab: light concrete 40mm, EPS (033) from 150mm to 200mm, reinforced concrete 300mm. Ufloor = 0,222 W/(m²K)

Windows: Uwindow = 1,019 W/(m²K)

Windows frame: KOEMMERLING, KBE 76, PVC double + single frame. U w-value = 0.88 W/(m²K). 

Windows glazing: Guardian – Climaguard 4/16/4/16/4 Ar90%. U g-value = 0.69 W/(m²K) g -value = 62 %

Heating system: Heat generation GAS condensing boiler

Ventilation: WOLF , CWL 300 EXCELLENT, Central balanced ventilation with HR & subsoil heat exchanger (air-soil) by REHAU, eff. specif. HRE: 82%

Image gallery

The ventilated facade, being on the outside of the structure, functions as a thermal buffer by reducing undesired heat gain during the cooling season, heat loss during the heating season and thermal discomfort due to asymmetric thermal radiation. It also maintains the exterior wall material dry, prevents condensation from forming within the exterior wall and rain water from infiltrating the building structure. These functions are explained in detail below.

It is considered to be the most efficient system to solve general insulation issues in buildings and to eliminate the thermal bridges and condensation problems. It is the ideal system especially for building renovations. It can be constructed in any climate zone, with the only difference in the thickness of thermal insulation that is required, which is depending on the building’s location. 

Investing in ventilated facades you save not just your money by reducing building’s energy consumption that is required for heating and cooling but also because of low maintenance and durability of your building.

The passive insulation air cavity combined with a proper wall insulation system helps save energy. When it is hot outside, this buffer zone behind the cladding system allows the hot air outside to cool off, shielding the interior of the home or structure from the thermal impact. Likewise, in colder climates or when there is cooler weather in any climate, this air space behind the cladding provides the same buffer zone to prevent the transmission of heat gain or loss which creates a more energy efficient building.

How it works?

Ventilated facade is formed by components that are attached to the primary structure of the building. On the building envelope is fastened a thick thermal insulation, a ventilation chamber and cladding system.

Thermal insulation

Thermal insulation reduces heat dissipation in the cold months and heat absorption in the warmer months, helping significantly save money from heating and cooling as well as greatly improves the thermal comfort of your home.

Ventilation Chamber

The air chamber, located between the cladding and the building envelope of the building, creates a natural ventilation by the so-called “chimney/stack effect”. During the heating season, the warmer air rises up through the building’s facade and escapes at the top of the chamber through ventilation openings on the facade cladding while fresh cooler air enters the building’s facade at the base of the chamber. During the cooling season, the chimney effect is reversed, but is typically weaker due to lower temperature differences.

This ventilation openings must be >=20mm and must be left whenever there is an interruption in the face of the facade cladding. To permit air circulation in the ventilated chamber, the air intake and output must be correctly proportioned. This permeability moving air diffuses water steam from the inside out and facilitates the ‘exhaling’ of the facade. Moreover, the air gap maintains the insulation material dry, prevents condensation from forming behind the insulation and rain water from infiltrating the building structure. Air gaps facilitate hygric redistribution and moisture removal by air exchange. 

Cladding system

Cladding system allows the heat absorbed by solar radiation to dissipate through natural ventilation of the air from the chamber. The system is installed on a metal hanging structure / battens  fixed to the frame of the building (building envelope) with layers of insulation.‎ Main function of the external cladding is to protect and insulate the building and to create an air cavity between external environment and the structural wall of the building.‎

Choosing the right material is not an easy task. You need to analyze the properties thoroughly, understand the pros and cons to find which one is more suitable. Be careful, the right choice can take your house to the next level in both form and function or it can reduce its structural integrity, aesthetics and value. 

Let’s explore the benefits of the most well-known cladding materials:

Brick cladding

Brick cladding

Brick cladding is one of the most commonly used cladding materials of the last century. Brick cladding improves the appearance of the building while protecting it from harsh weather. It is preferred over other materials because of the numerous benefits it has on offer. The foremost benefit is durability. Bricks are highly durable, non-toxic, fire resistant and cost efficient. Brick cladding supply premium sound insulation and weatherproofing. This highly thermal efficient material if combined with a proper external wall insulation system proves to be a smart investment. You can save up to 25% on energy bills and is considered low maintenance. It is reusable and recyclable, making it a great building option. Bricks are available in a wide range of colors, finishes and patterns.

Timber cladding

Timber cladding. You can opt for vertical, diagonal, horizontal boards or shingles.

Timber cladding has increased in popularity in recent years as a naturally recyclable material, which  also enhances the appearance of your home and reduces energy consumption for heating and cooling.  It has an excellent sound absorption properties, making your home a more peaceful place. This practical and sustainable external finish is available in a wide variety of wood types, grades and profiles to suit your wall cladding. Canadian western red cedar and Siberian Larch are among the most popular softwoods used today. Sweet chestnut and European oak are two hardwood species which can also be used in timber cladding projects.  

Tile cladding

Whether natural stone, ceramic or porcelain tiles add a certain sense of elegance, purity or timelessness to your home. Choosing a sleek modern designs or opting for a natural textured look, tiles are extremely versatile, incredibly durable, long lasting and easy to maintain. They also act as insulators raising you homes energy efficiency. Tiles come in a variety of colors, finishes, shapes and sizes.

Composite timber cladding

Composite timber cladding

Composite timber cladding is a unique combination of recycled wood and plastic, combining the traditional appearance of wood with the durability of an engineered composite. It is available in a range of colors, widths and styles to suit both contemporary and traditional style homes.

Metal cladding

Aluminium, zinc, stainless steel, corten (pre-weathered steel) and copper are all available in a variety of colors and profiles, offering a contemporary, industrial look to your dwelling. The most common types of metals used as cladding are steel and aluminum. Aluminum is the most corrosion resistant. The durability of metal cladding depends on the type of metals used,  the  building’s exposure  type and the effectiveness of corrosion-protection system. Metal cladding can be attached onto an exterior wall in several ways, such as profiled or composite metal cladding.

Composite metal cladding

Georg Zielke is an independent architect with many years of experience in environmental and economic planning for housing. His office is in Darmstadt, Germany. Since 2002 he specializes in the planning and construction of residential buildings with the passive house standard.

His main interests and competences are:

• Construction of cost-effective and environmentally friendly housing projects
• Use of ecological building materials
• Development and reconstruction of existing properties
• Standardized building design
• Use of recyclable materials

On my last trip to Darmstadt, I visited a housing complex of seven terraced houses in Kranichstein, planned and realized by Georg Zielke.

These residential units, standing at least 30 cm above the ground, were planned and erected with prefabricated timber panels. The timber-frame construction was built on self-made cellars (concrete shuttering blocks) which were placed and were ready for construction within 4 weeks. Due to 30 cm thick insulation the house is heated by the warmth emitted by sun light, people and appliances.

The floor plans were designed individually according to the client’s wishes. Each house has a ventilation system with heat recovery. The fresh air coming into the homes through an insulated duct that passes through the heat exchanger core where it gets heated up by the outgoing stale air, which is collected from the bathrooms, kitchen and sometimes utility or laundry room. After it is heated, the fresh air is ducted throughout the living areas and bedrooms. Stale air is pulled from the home and enters the other side of the core where its heat is given to the fresh air, before it is exhausted from the building via ductwork. The heating and hot water are supplied via a district heating system (DHN).

The facades were clad with untreated, rough sawed larch wood. The vertical timber cladding is structured with colored aluminum panels – a different color is assigned to each house. (The aging processes may and should be visible: The older the house gets, the more silvery the larch boards become and the more colorful the panels appear. This effect is starting to be visible after about 10 years. The blinds integrated in the facade provide summer protection against overheating. The indoor climate is therefore extremely comfortable in both summer and winter.

Selected project details:

• energy-efficient construction
  (30cm exterior insulation, ventilation system with heat recovery,  airtightness, thermal bridge free)
• rainwater utilization system
• ecological building materials
  Timber construction: Great importance was given to the wood protection. Chemical wood preservation was deliberately avoided.
• green roofs

The site was completed in 2015, including the roads and green areas. Planning and building at the site took more than 10 years in total. An essential feature of the area is the reduction of car traffic. The quarter was designed car free and is very well connected to the public transport system of Darmstadt with a newly built tram.

Walking around the neighborhoods of Agria, a delightful semi-rural location on the outskirts of Volos, three houses stand out. Three family houses in a row with a “Passive house certification” wall plaque. These are huge 477m² buildings with exquisite view to Aegean Sea that combine high energy efficient characteristics with building elements of Mount Pelion traditional architecture.

The facades of the houses combine stone cladding with white stucco and wood details. Their style matches the area’s residential houses. The facades look very traditional but the sides are quiet modern and minimal.

West facade. Main entrance of the houses

On the ground floor, a bright living room with a freestanding fireplace, occupied by an open plan kitchen with a modern island and a dining area. Located on the same floor a small WC. A metal staircase with wood cladding leads to three bedrooms and a bathroom in the upper floor.

The house’s geometry, orientation, size and layout of the openings and high thermal conductivity building materials achieve thermal comfort, low energy costs and healthy indoor air quality. 

The property benefits from

• 15cm EPS external insulation
•  wooden windows frames with double glazing filled with argon gas
• thermal bridge free construction
• ventilation unit with heat recovery (separate unit for each house), additional subsoil heat exchanger
• air-tight dwelling envelope (n50 = 0.6/h)
• improved flat plate solar collector stratified solar storage 300lt for each house
• used local building materials

Detail of the west facade of the south house

South facade

North facade

Air ventilation with recovery

Mechanical ventilation system with heat recovery provides always fresh and clean air all year round, while preventing the escape of heat from the houses. These three semi-detached houses have a pleasant (cool) indoor climate even during excessively hot periods.

Cross-section of the Agria, Magnesia Passive House including the air flow during winter and the individual zones.

Cross-section of the Agria, Magnesia Passive House including the air flow during summer and the individual zones.

Why don’t you have to heat in winter?

The sun shines through the windows every now and then in winter, and each person delivers 80 watts of heating power. In addition there is the heat emitted by electrical appliances, appliances for lighting and cooking emit plenty of heat. The reason we have to heat conventional buildings is because a lot of heat is lost from window ventilation and walls.
The solution for a home without a heating system is in theory very simple. The heat losses must be reduced to such a degree that less heat flows out of it than the heat supplied to it by sunlight and internal sources (people, stoves and appliances) free of charge. Every polar bear demonstrates that it is possible to live well with sufficient thermal insulation even in the arctic. In principle, buildings can be so well insulated that the solar radiation and the internal heat sources suffice for heating. An overall cost analysis shows, that it is cheaper to insulate a little more and heat less.

When a house needs to be heated costs occur for the heat generator, the heating surfaces and the piping. The key of the Passive House concept is to save the costs of heating surfaces and their piping by using the already present fresh air supply for heating.

Cross-section of the first Passive House in Darmstadt – Kranichstein.

The ventilation system required for this is already available in an energy-efficient house, to avoid the high window ventilation heat losses with the use of a heat-recovery system. In the passive house, the insulation thickness is now chosen so strongly that the necessary amount of required fresh air, for hygienic reasons, suffices to transport the needed heat to the rooms. The heating of the air is made possible via a small heating coil installed in the ventilation system, radiators are only required in the bathroom. For a fresh air heating system to be able to heat a building without having to circulate the air, the heating requirement must not exceed 15 kilowatt hours per square meter of living space per a year. This corresponds to the energy content of 1.5 liters of heating oil per square meter. The required heating power is then 10 watts per square meter. This means that a 150 sqm single family home does not need more than the equivalent of 225 liters of heating oil for space heating and a heating output of 1.5 kilowatts per year. This corresponds to the performance of an electric fan heater.

If a building requires more than 15 kilowatt hours of heating per square meter, the required amount of fresh air for heat transport is insufficient. Additional heating surfaces must then be installed and piped. The additional costs for that affect in connection with the higher heating bills, the building, making it ultimately more expensive than a passive house.

“Despite the cold winter morning, the neighbors’ kids up early making a racket in the street, riding their bikes and playing with their dogs, in your cozy bedroom it is quiet and peaceful. Eventually you stir as some warm rays of winter sun poke through the clouds and bounce around the room, stimulating your senses ready for the day ahead. You sit up refreshed after a great night’s sleep to a room full of fresh air. You throw on a t-shirt and feel a twinge of guilt that there is no need for a jumper even though it is so cold outside, but then remember that you have not turned the heater on all year, so you start your day comfy and guilt free.” From the book ‘Positive Energy Homes: Creating Passive Houses for Better Living’ by Robin Brimblecombe and Kara Rosemeier.

How does the passive house behave in winter?

• Due to low heat losses, passive houses only have to be actively heated in cold months November, December, January and February. If someone wishes to open the windows for a quick airing despite the plentiful fresh air supply through the ventilation, he can do that, but it is unnecessary, leads to dry air and increases heating costs.
• With properly installed insulation, unheated rooms are almost as warm as heated ones. This means that unheated bedrooms have pleasant temperatures even in the winter. This allows a year-round very comfortable sleeping with light bedding. In the winter if you want to sleep colder than in the summer, you can tilt the bedroom window at night. Thereby the air will not get fresher, but colder.
• Cold winter air contains very little moisture. The air in the house therefore gets drier the more air is released. This effect occurs regardless of whether it is ventilated via the windows or via a ventilation system, since the same external air is always supplied back in.
• In homes with little moisture sources, for example with few residents, few plants and occasional cooking the hygienically recommended fresh air supply can on cold winter days lead to unpleasantly dry feeling air. In these rare cases, higher humidity can be achieved by introducing additional moisture sources such as plants, laundry drying or humidifiers.

How does the passive house behave in summer?

Saving energy via the ventilation system is only possible in winter. From spring to autumn you can ventilate by opening the windows, just like in normal buildings. In summer, all insulated buildings behave the same. The insulation protects against external heat, but has also the effect that when the heat gets inside, for example by open or not shaded windows, it remains in the building, unless it is ventilated away at night. This effect occurs in every insulated building, not just in Passive Houses.

The Passive House ventilation is not powerful enough to ventilate away this heat. Heat that has penetrated inside can only be vented out through the windows. This works very well when two to three windows are not only tilted but fully open throughout the night. The long airing through the night stores the coolness inside the building. Then, during a hot day, if the windows are kept closed, which is easily done in a Passive House because of the ventilation system, and targeted windows shaded, the building remains pleasantly cool during the day. The building offers comfortable living occupied even on very hot summer days.

The additional costs to build a new house or upgrade an existing one, in order to meet the Passive house criteria, are not very high. The heating energy consumption is almost zero and, the most important for low operating costs, it requires very little building technology. The low additional costs you can save through the European subsidy (for example “Εξοικονόμηση κατ’ οίκον” in Greece) and over the years additional energy cost savings easily again.

How Passive House can benefit your life?

• High quality energy-efficient buildings with low ecological footprint
• Maximum level of comfort both during cold and warm months
• Affordable, low operating energy costs
• Healthy living conditions. Excellent quality of indoor air and temperature
• Well-being

How can you keep your home warm during winter without consuming too much energy?

The idea of Passive house rests on designing a building which will maintain a comfortable and healthy interior environment (living conditions) across all seasons of the year, without excess energy consumption. The excellent quality of indoor air, free from pollen and dust particles; the maintenance of desirable levels of humidity and the mild and comfortable indoor temperature across all seasons, are criteria of Passive house.

The criteria for a passive house are attained by means of careful and smart design and the implementation of the five principles for passive houses: insulation, energy efficient frames and glass panels, air conditioning with heat recovery, the airtightness of the construction and the lack of heat bridges.

	Insulation All exterior walls must be very well insulated. Thickness and quality of the insulation help significantly save money as well as greatly improve the thermal comfort of your home and protects the environment by reducing the heating energy requirements.
	Building’s airtightness In combination with, a continuous, strong, stiff, and durable air impermeable barrier will stop uncontrolled air flow which may carry water vapor, and become trapped, condense, and create microbial growth issues. A properly insulated and air-tight dwelling envelope will keep heat inside the building in winter, while blocking it in the summer.
	Lack of heat bridges Another important aspect is absence of thermal bridges. Air needs an opening or hole to flow through and a driving force to move it. Uncontrolled and unintended air-exchange often cause several building performance problems. They are simply fragments of the building envelope where thermal performance is much reduced in comparison to the neighboring construction parts. The weakened thermal insulation can be linear (i.e. the gaps at the joints of insulation boards) or pointed (penetrations of the insulation layer). The thermal bridges not only cause the heat to escape. The structure can get colder and the vapour can condensate in it, making the structure or insulation wet and even leading to the growth of fungi or mould. The best method to verify the insulation quality is thermal imaging. Other essential components include energy efficient frames and glazing panels and a heat recovery ventilation system.
	Energy efficient frames and glass panels  The frames’ profiles must be well insulated and fitted with low-emissivity coatings, multi-pane glass panels, argon or other gas-filled to make windows more energy-efficient and decrease heat transfer/flow through them. There are no special requirements for the size of the window surfaces. A south orientation of the main window areas is beneficial/ profitable, but not mandatory. In the north, the window area should be kept rather small. The windows can be opened at any time in the winter, but due to the ventilation system this rarely makes sense.
	Ventilation with heat recovery In new buildings, the window ventilation causes about half of the total building heat losses. These high heat losses can be reduced at least 75% by installing a mechanical ventilation system with heat recovery. The ventilation systems are in passive houses under no circumstances necessary because the building could “breathe” less due to the good insulation and airtightness. At the same time, heat recovery ventilation with provides a highly comfortable and completely draft-free form of fresh air supply, control humidity and offer maximum energy efficiency due to heat recovery. So, you can easily dry the laundry in the apartment, leave the bathroom door after showering and set up any number of plants. Another advantage: If you suffer from a pollen allergy, you can also equip the ventilation system with a pollen filter. Ventilation with heat recovery is a very simple technique. It is the only passive house component that has to care for once a year. It is necessary to clean the device, replace the supply air filter and wash out the remaining air filters. The operating effort is limited to adjust the desired amount of fresh air on an operating unit.

Is passive house standard reliable?

It started out as a construction concept for residential buildings in Central Europe. Since the construction of the first passive house in 1991, thousands of residential buildings and numerous schools, kindergartens and companies have been built in the passive house standard. The passive house is a further development of the low-energy house, which has been tested for decades. Today, the Passive House Standard can be implemented in all types of building almost everywhere in the world. The European Union aims to build passive-house buildings from 2021 onwards.

The first phase of the WohnSinn 1 project was initiated in 2003, a 3860 m² multi-family building comprising 39 apartments, it was judged to be so successful that a second phase of 2,721 m² (living space) building expansion involving 34 apartments was built in 2008 the WohnSinn 2. The concept was developed over a number of years, aiming to  create a diverse yet socially integrated community of households. People with different incomes, ethnicity, backgrounds, levels of physical ability or marital status are living together. Some families purchased their homes others rent them while others rent with welfare assistance from the Government. It would appear that this ‘social experiment’ has been very successful. “As a practical example of the benefits of living in such a neighborhood, it was envisaged that families with young children could call upon their elderly neighbors from time to time to assist with child minding when the need arises.”

Design features

The development consists of a three story south-facing U-shaped layout with some of the units being two story  while others single story. All of the upper  stories are accessible via shared terraces which are connected to a lift at the northeast corner. The entire structure is thus barrier free in terms of access. All of the homes have dual aspects, the two south-north oriented blocks have east and west facades while the connecting east-west oriented blocks have south and north facing facades. All of the ground floor apartments have terraces, many of which have been planted and provide a valuable space.

The corners of the apartment blocks are cleverly used for community purposes, including a day room winter garden and library to the northwest, sauna, guest apartments, a creative room for kids to the northeast and meeting rooms to the southwest. The building is accessible and contain four wheelchair-accessible apartments.

 A landscaped mound in the central courtyard hosts an underground ‘bunker’ room, used by the community to store food and bulky non-perishables that require cool temperatures.

The load-bearing structure consists of prefabricated concrete elements in a cross wall construction. The thermally insulated shell  is made of prefabricated wooden wall elements. The walls have thick cladding of insulation (38cm high density polystyrene) and damp proofing. During construction a rainwater collection was installed with an underground tank for watering the gardens and green roof. The windows where fitted before the external insulation was applied to ensure that an airtight connection between the frame and the shell is achieved. The external insulation was fitted afterwards to cover the window frame thus reducing heat losses through thermal bridging.

Perceived Benefits of the Passive House Standard

The multi-family building of WohnSinn was built to the passive house standard, offering high thermal comfort, healthy indoor air quality, bright living spaces, with low heating cost and a high level of sustainability.

Due to the good insulation and the ventilation system with heat recovery, the heating energy consumption is almost zero. The building losses so little heat that no conventional heating is needed. The living spaces  are mostly heated by passive energy without any boilers/radiators.

Heat input is provided through:

• large windows
  which allow the warming sunlight to get in,
• the radiation of body heat of the occupants 
• the waste heat
  from electrical appliances and from cooking and bathing. Small radiators are running via the hot water supply in bathrooms.

Heat loss is prevented  with the triple glazed windows and doors with triple seals to prevent droughts. Each apartment has a separate ventilation system with heat recovery so that fresh cold outside air can be warmed up to a comfortable temperature by using the heat of the warm stale indoor air as it is extracted (unit recovers over 80% of the heat).

Every household has direct control of their own mechanical system, the control of heating and ventilation is very easy and fairly simple. There are only two adjustable elements: A thermostat for adjusting the need for heating and air exchange rate. There are three levels of air exchange rate; namely low, which is used when the units are left unoccupied during holidays, normal, for everyday use, and high, when there is a need for greater air change rate such as during a party or family gathering. Maintenance is low due to the simple technology: Once a year, two filters have to be washed out and one filter has to be changed. Because WohnSinn is a “single” building and not separate houses heat loss through the walls and roof is considerably reduced.

All residents have the option to invest in the photovoltaic power plant located on the roof of the apartment complex, which provides an annual return on investment of 3 – 4%. Due to the passive house standard and a self-produced power supply via photovoltaic systems on the roof, the energy costs are low.

Selected project details of the WohnSinn apartments:

Architect: Petra Grenz, faktor10 GmbH
Building services: WohnSinn1: Norbert Stärz, Pfungstadt / WohnSinn 2: Hans Baumgartner, Mörlenbach
Principal Construction Contractors: WohnSinn1: Tichelmann & Barillas, Darmstadt WohnSinn2: Büro bauart, Lauterbach, Darmstadt
 

Treated floor area in PHPP: 3.885 m2 WohnSinn1, 3.097m² WohnSinn2
Construction type: Concrete core made with prefabricated elements with facade comprising a timber frame structure

Annual heating demand (PHPP): 15 kWh/(m²a)
Heating load (PHPP): 10W/m2
Roof: Reinforced concrete slab in 220 mm thickness, 180 mm Polyurethane foam insulation WLG 025, U-value: 0. 135 W/(m2K)
Floor slab: Reinforced concrete slab in 25 cm thickness, underside 300 mm insulation, Thermal Conduction Group 035, U-value: 0.11 W/(m2K)
Walls: 300mm Styropor insulation on concrete elements or 300mm Isofloc in the timber frame elements. U-value: 0.12 W/(m²K)
Windows frames: Fa. Kochs, eCO2, Profile Kömmerling, Thermally insulated plastic frame. Uf = 0.8 W/(m²K)
Glazing: Triple glazing, Ug = 0.6 W/(m²K) g-value = 50%

Air tightness (PHPP):  n50 = 0.35/h
Ventilation: Vallox KWL 90, counter flow heat exchanger. 75% efficient (Manually controlled)
Average air change rate: 0.4/h when occupied 0.25 – 0.3/h when not occupied
Heating installation: water to air heat exchanger connected to a district heating system
Domestic hot water: District heating + 25m² thermal solar collectors (used on WohnSinn2)
Renewable energy production: 250m2 of photovoltaic panels installed in 2009 – productivity not yet determined Jahr 2009