"Only primitives & barbarians lack knowledge of houses turned to face the Winter sun" Aeschylus 524 – 456 BC
"Building to code is the worst possible building that you’re allowed to build by law"
Passive house windows
A passive house is a voluntary standard for energy efficiency in a building by reducing its ecological footprint, in other words, passive house buildings require little energy for space heating and cooling. Passive House Design was initially found in Saskatchewan, Canada in 1977 then the principles of Passive House Design were systematized by Bo Adamson and Wolfgang Feist, who founded the Passive House Institute (Passivhaus Institut) in 1996 in Darmstadt, Germany.
Modern windows with a high level of thermal insulation today supply more energy than they lose. They play a significant role in planning an optimal building related to energy, for example for passive houses. By integrating high quality thermal insulation, passive houses do not require a supplementary heating system, due to the passive use of solar irradiation through the windows and the heat discharged to the interior by occupants and electrical appliances. According to the certification criteria of the Passive House Institute in Darmstadt, Germany, a passive house must obtain a heating demand of maximum 15 kilowatt hours per square meter per year. There are also specific limits to be observed for primary energy demand, air tightness and minimum efficiency. Precise and extensive planning is required to reach these values. In addition to the particularly good thermal insulation, passive houses avoid thermal bridges and have a high level of air tightness. To fully utilize the positive effects, certain things must be taken into consideration when selecting, planning and installing the windows.
A building standard that is truly energy efficient, comfortable, affordable and ecological at the same time.
Passive House is not a brand name, but a construction concept that can be applied by anyone and that has stood the test of practice.
Yet, a Passive House is more than just a low-energy building.
- Passive Houses allow for heating and cooling related energy savings of up to 90% compared with typical building stock and over 75% compared with average new builds. In terms of heating oil, Passive Houses use less than 1.5 liters per square meter of living space per year – far less than typical low-energy buildings. Similar energy savings have been demonstrated in warm climates where buildings require more energy for cooling than for heating.
- Passive Houses are also praised for their high level of comfort. They use energy sources inside the building such as the body heat from the residents or solar heat entering the building – making heating a lot easier.
- Appropriate windows with good insulation and a building shell consisting of good insulated exterior walls, roof and floor slab keep the heat during winter in the house – and keep it out during summer.
- A ventilation system consistently supplies fresh air making for superior air quality without causing any unpleasant droughts. This is e.g. a guarantee for low Radon levels and improves the health conditions. A highly efficient heat recovery unit allows for the heat contained in the exhaust air to be re-used.
The vast energy savings in Passive Houses are achieved by using especially energy efficient building components and a quality ventilation system: There is absolutely no cutting back on comfort; instead the level of comfort is considerably increased (see Comfort).
The window in a passive house plays a prominent role in two ways – firstly, the heat loss despite large glass surfaces can be reduced and secondly, windows increase the possibilities for heat gain through solar irradiation.
Internorm‘s highly thermally insulating energy saving windows fulfill this seemingly contradictory dual capacity exemplary: Triple heat protection glazing achieves Ug values of up to 0.5 W/m2K and g values (overall energy transmission factors) of up to 62 % – depending on coating and gas fillings.
In comparison Ug values of conventional windows often lie at around 1.4 W/m2K.
Besides the glazing however you have to consider the insulation of the window frame as well as thermal bridges at the glass edge and in the connecting area window to wall.
Spacers form thermal bridges, they are usually made of aluminum. Especially for use in passive houses particularly well thermally insulating window frames were developed, which also reduce the glass edge losses.
Stainless steel spacers further reduce losses at the glass edge. For passive house certified components thermally optimized systems – like the Internorm ISO spacers – are used. Following the automobile industry all glass panes are glued to improve structural stability.
Essential Principles For Construction Of Passive House Windows:
- Highly thermally insulating glazing
- Highly thermally insulating frame
- Thermally optimized composite edge
- Expert installation, thermally optimized
A passive house provides consistent, comfortable temperatures in winter, as well as in summer without using conventional heating or air conditioning systems. Using the existing temperature provided through solar irradiation through the windows as well as the heat from appliances and inhabitants is sufficient, the necessary heating energy for a passive house is only 10 % of that needed for a conventional house.
Optimized energy demand
This results in an annual heating demand of not more than 15 kWh/m2a. The overall energy demand including warm water and household electricity for a passive house is less than 120 kWh/m2a. The heating load of a passive house is not more than 10 W/m2, for a room of 30 m2, this results in a heating load
of approximately 300 Watts – just to illustrate: the heating power of a tea candle is 30 Watts already. This means that 10 tea candles are enough to heat 30 m2 in a passive house. These extraordinary savings are rooted in the two basic principles of minimizing thermal loss and optimizing thermal gain.
Due to the powerful insulation the heat stays inside the building, all surrounding surfaces are equally warm. For this reason there is no radiation asymmetry (heat radiation) originating from exterior walls in a passive
house, and also the resulting drought phenomena are avoided. The reverse conclusion would be that heat stays outside in the summer to avoid overheating. This means that in a passive house a consistent living climate is retained throughout the whole year – this provides a high degree of comfort for the inhabitants. Passive houses also make use of highly efficient air conditioning systems to prevent mold growth, dust and any resulting allergies.
Reducing Costs and protecting the environment
As the energy demands of a passive house are reduced by up to 90 %, heating costs and therefore CO2 emissions can be reduced drastically – compared
to a conventionally constructed building, on average 4.000 kg of greenhouse relevant carbon monoxide are avoided each year.
This would correspond to driving about 27.000 km with a typical 6 liter car. Therefore constructing energy efficient passive houses supports climate protection sustainability and saves on limited resources, such as oil or gas.
WHAT IS IMPORTANT FOR PASSIVE HOUSES
One of the major characteristics is the active utilization of existing energy – minimizing thermal losses and at the same time optimizing thermal gain, these are the basic principles. But merely combining passive house certified
components is not enough to reach a passive house construction standard: The whole thing is more than the sum of its parts – mutual interactions between the distinct components necessitate integral planning to fulfill three basic demands:
- Heating demand < 15 kWh/m²a
- Primary energy demand (heating, warm water, house appliances) < 120 kWh/(m2a)
- Pressure difference air exchange n50 < 0.6 h-1, i.e. at a pressure difference of 50 Pascal the air flow must be
less than 60 % the building’s volume per hour.
The passive house needs an impermeable outside shell and optimized thermal insulation with integrated ventilation in both directions: Fresh air is sucked into the building underground through the ventilation pipe, pre-heated by the earth, and led to the heat recovery system. There the energy of the used air is
passed on to the fresh, filtered, cold air using a heat exchanger. Here the energy stored in used air, which would normally be lost in traditional airing, is utilized. From there, air is led into the living areas and distributed with special
nozzles in order to avoid droughts. The air is sucked out of sanitary areas
and the kitchen, in order to avoid the spread of unpleasant smells throughout the house.
PASSIVE HOUSE CERTIFIED WINDOWS & DOORS
Internorm is number one manufacturer of passive house windows and the only window manufacturer in Europe with nine passive house certified components. That means that nine window and door systems have been certified by the "Passivhausinstitut Dr. Wolfgang Feist".
TIPS FOR PASSIVE HOUSE BUILDING STANDARDS ACC. TO PASSIVHAUSINSTITUT
- Good thermal protection of the facade through appropriate insulation (U < 0.15 W/m2K)
- Super glazing ( 48MM - 52MM triple glazing ) and super window frames, that means U value < 0.80 W/m2K and g value around 50 %
- Avoid thermal bridges
- South facing of large windows to use the sun as source of energy
- Passive pre warming of fresh air – air can be warmed up through earth heat exchanger
- Heat recovery from used air through counter-flow heat exchanger
- Water heating possible through renewable energies
- Energy saving appliances in the household