Lauded for incorporating warm, natural wood finishes to create a “comfortable place to dwell and reenergize,” the jury of the 2013 Solar Decathlon has named Czech Technical University as winner of the competition’s “Architecture Contest,” placing them third overall.
Based on a “house within a house” concept and inspired by the Czech tradition of spending weekends in the country, the “AIR House” features a flexible, open interior that is protected by an intelligent second skin - a “solar wooden canopy” that generates energy and provides hot water via photovoltaic and solar-thermal panels. Read for the team’s project description.
The AIR House design reacts to the contemporary demographic development in the Czech Republic; where senior housing presents a very imminent social topic (currently 20% of all households).
Our main inspiration comes from a typical Czech custom of spending weekends in "chata" – a cottage or cabin out in the country. During the socialist times from 1948 to 1989, the majority of the population had no money to invest in a „proper country house“, and a very unique type of unorthodox, folk architecture had developed for over four decades in the former Czechoslovakia. In composing the house’s volume and functions, we worked with the traditional features of a typical Czech farm house with shaded porch and barn in an L-shape configuration that creates a protected courtyard connected to the farm yard.
The concept combines a minimum interior living area with a generous outside area. The economy-sized disposition is based on the tradition of minimal housing, where an ingenious architectural design saves space and therefore saves purchase and operating costs. The flexible living space accommodates kitchen, living, dining and sleeping space. The technology module features a bathroom, technical room, outside kitchen and storage. The sun deck can hold different activities such as cooking, gardening, relaxation and storage. The integrated edible natural garden functions as a mediator between the house and the surrounding nature.
House Within a House
The composition of AIR House’s main volumes is primarily based on the “house within a house” concept which works with the principle of two skins.
The First Skin is formed by a thermal insulation envelope of the living area that is made of massive wood panels in combination with natural wood fiber thermal insulation. Under this skin the main volume and all indoor functions of the house are contained.
The second Skin, formed by a solar wooden canopy, protects the First Skin from thermal stress caused by the sun and the wind, and generates electric energy and hot water via photovoltaic and solar-thermal panels attached to the canopy´s structural elements.The space between the two skins generates tension between the interior and exterior. It creates a unique atmosphere, a play of light and shadows. From further away, the house looks very compact and its volume appears a simple cubic shape.
An important aspect of the AIR House design is the creation of a strong link between the house´s exterior and interior. Our aim was to extend the relatively modest interior living space outside and allow the users to benefit from a shaded terrace for their activities. This terrace, thanks to the glazed wall that divides it from the interior space, can be fully functionally connected to the interior and serve many purposes – as a meeting space for social activities, as a dining room, kitchen, movie theater etc. Also, with the sliding doors open, the interior becomes immediately part of the exterior, and during summer evenings the inhabitants can fully enjoy the fresh breeze while still being protected from the eventual rain shower.
An edible garden is integrated in the terrace deck and acts as a mediator between the house and the surrounding nature.
The AIR House energy concept is simple and ecological. The layout combines a minimum interior living area with a generous outside area. The goal is to place a maximum of functional units outside the air-conditioned area and thus minimize the energy needed to maintain interior comfort. The AIR HOUSE is designed as a zero‐energy house. It obtains all the energy needed for the household, and for the maintenance of the optimal interior climate, from solar radiation. Low material, water and energy consumption is also important to us.
50 m2 of PV panels generate all the energy needed for operating the house. AIR House is equipped with 30 amorphous crystalline panels 350x210x8mm 185 Wp. During the contest week in US, electrical energy will transfer to the Solar Village micro grid. For the use in Czech Republic, the house features a standalone PV unit for ensuring the operation of common appliances with lower power consumption and testing and monitoring the energy self-sufficient concept of the AIR House.
In the Czech Republic climate, the house will be ventilated naturally most of the year. During winter and for the competition purposes, we will use recuperation of waste heat. Heat recuperation ventilation system ensures optimal air exchange and during ventilation minimizes heat loss, which represents up to 40% of the entire loss of the building in standard family houses. In the AIR House, the interior air quality is provided by a Duplex RB4 EC ATREA hot-air ventilation unit. The hot-air ventilation unit is connected to an outer loop control and intelligent house control with data collection.
Solar Thermal System
The domestic hot water in AIR House will be provided by two flat-plate solar thermal collectors by Regulus, a purely Czech-owned company. Solar system operate on the principle of transforming solar energy into heat. The system is able to utilize as much as 80% solar energy. The heat trapped inside the collector is transferred by special antifreeze solar fluid into an integrated heat storage tank IZT ATREA (Atrea). In the central Europe climate conditions, the solar system covers 50-60% of the domestic hot water needs throughout the whole year, 100% in summer and 10% during winter months. In periods of low solar insulation, the solar hot water system will be supplemented by an air-to-water heat pump.. Our solar thermal system is designed to cover all domestic hot water needs during the Solar Decathlon display.
Considerate water handling is another priority of the AIR HOUSE concept. In house, drinking water can quickly turn to waste, but there are many ways it can be reused in the garden. A grey water system collects water from the showers, wash basins and washing up, filtering it and re‐using it to irrigate plants and thus reduces water consumption by 20%.
The AIR HOUSE bathroom is fitted with a low flush toilet. We use Axor Starck Organic bathroom mixers and shower (Hansgrohe), which are economic in terms of consumption; their water consumption is 60% lower than of standard mixers. The extremely efficient shower spray is made up of 90 jets and is highly functional, bathing the entire skin. Technological solution of the mixers prevents water from coming into direct contact with the mixer body. This keeps drinking water free from lead and nickel contamination.
Our health enhancing strategy is not limited to a technological solution or use of materials that present no health hazards. According to the famous quotation of Winston Churchill (1943) “We shape our buildings, thereafter they shape us“, our approach is more complex. We choose materials in accordance to how they affect all 5 human senses. To respect human circadian rhythm, we focus on visual comfort; we program the artificial lighting to correspond to natural lighting conditions.We believe, that the choice of materials defines the quality of the inner environment.
The AIR HOUSE is made entirely of wood, not only the load‐bearing structure, but also the thermal insulation, facade, finishing and furniture. We use an innovative massive building system ‐ a so called Cross Laminated Timber (CLT) made by Stora Enso. The wood in the CLT is from sustainably grown forests, and is laminated with nontoxic glues. The panels are strong enough to be used in earthquake or hurricane prone areas. The computer numerically controlled (CNC) cutting process done by Dřevostavby Biskup allows the panels to be cut precisely and meet very tight tolerances. Because the panels are solid, there is little potential for airflow through the system. Modular furniture units made of CLT panels, at the same time construction components of the house, function as elements of structure and storage. In the interior, they are visible, and create a pleasant, warm living climate.
Vapor Permeable Construction
Due to a diffusion-open structure, AIR House can breathe. The exterior weight-bearing structure made of massive CLT panels is equipped with thermal insulation panels. The interior side of the sandwich panel made of Steico wood fiber thermal insulation is shielded with an OSB board, the exterior side is covered by a DHF fiberboard. The interior CLT panel along with the OSB board function as a so-called vapor retarder not inhibiting vapor admission into the construction, only limiting its amount. Diffusion-open constructions are being used for hundreds of years in the form of monolayer stone, brick, clay or massive wood constructions.
Radiant Cooling and Heating
The primary system of the AIR House low-temperature heating and high-temperature cooling is provided by radiant chilled ceiling panels REHAU. Sheets of plasterboard panels with in-milled pockets and embedded PVC pipes are the basis. The cooling performance is up to 75 W/m2. From the heat comfort point of view, low air flow whirling a minimum of dust and microorganisms in the room, is an advantage. Compared to conventional heating, the room temperature is steadier which enables its decreasing by 1 – 2°C without affecting heat comfort of the inhabitants. This effect enables us to save a considerable amount of energy.
Manufacturers claim that, compared to a standard light bulb, LED lighting saves 85% of energy and their life span is 35 times longer. In the AIR House, LED light sources are ideal and in the exterior, they are used exclusively. In the interior, we use LED lighting only in some places and with due consideration (the kitchen counter, indirect lighting in the bathroom, overall lighting of the living area) and we supplement it with local bulb lighting. Why? The human organism functions in a certain natural – circadian rhythm (in Latin circa - roughly, diem – day). It is operated by the so-called inner biological clock. In a natural environment, its most important synchronizer is a regular variation of light and darkness. In an environment with mostly artificial lighting, the color spectrum of the light source is crucial. The blue light, so typical for LED, stimulates activity. On the contrary, in the evening, full-spectrum bulb lighting is advisable; it endorses production of melatonin, the hormone of sleep and physical regeneration.
In the AIR House, the measurement and regulation control system (MaR) in combination with the KNX smart home installation creates a communicating system with a unified web control for PC and mobile equipment. The intelligence of the system lies in its timely reaction to the needs of the house inhabitants and the outside weather conditions.
The measurement and regulation system (MaR) provides monitoring of all the house technologies, interior climate regulation and fresh air supply in a power mode as effective as possible. The interior climate quality is dependent on a precise control of interaction between the heat recovery ventilation unit and the radiant panels.
Smart Home Installation
The smart home installation (KNX) provides interior and exterior light comfort via dimming LED light sources that react to the Sun light intensity. The intelligent control can also be used to set and operate thematic lighting scenes.
Heating and Cooling
The radiant heating and cooling system is controlled by an automatic AS525 unit provided by the SAUTER company. The unit measures temperatures, humidity, flowage and other physical values. A servo regulates water mixing in the valves, controls operation of pumps, exhausters and flaps. Furthermore, it monitors and optimizes all technical equipment of the building concerning heating and cooling technology, air-conditioning, and water utilization.
More information on the AIR House can be found on the team’s official website.