- 1. High levels of comfort
- 2. Consistent fresh air all throughout the building
- 3. Structural longevity: mould free buildings with a highly reduced risk of moisture damage
- 4. Extremely low heating and cooling costs, despite rising energy prices
- 5. A radically improved indoor environment, avoiding the risk of Sick Building Sindrome
PASSIVE HOUSE BUILDINGS: DOING MORE WITH LESS
In a league of its own
Passive House buildings combine unparalleled comfort with very low energy consumption. Quality design and craftsmanship paired with superior windows, high levels of insulation and heat recovery ventilation are the key elements that set Passive House construction apart. In terms of appearance, however, these extremely efficient buildings blend in perfectly with their conventional neighbours. This is because Passive House describes a performance standard and not a specific construction method: while Passive House buildings must meet specific energy demand targets, building designers are free to choose how best to meet them.
Adapted to the local climate
The Passive House Standard can be implemented all over the world and the general approach is always the same. Depending on the local climate, the properties of individual components will vary.
In hotter climates, for example, special attention should be paid to passive cooling measures, such as shading and window ventilation, to ensure comfort during the hot months. The individual characteristics of any Passive House should be optimised to the local conditions.
More Comfort, Less Energy. But, How?
With Passive House, careful planning and execution is essential. This attention to detail ensures a minimal energy demand: 10 tea lights or even the body heat of 4 people could keep a 20 m² Passive House room warm in the middle of winter, even in extremely cold climates. In reality of course, Passive Houses are not heated with tea lights; they use efficient heating systems and draw on the ventilation that is in any case needed to ensure high indoor air quality. Passive House buildings provide impressive levels of comfort in the summer as well, making air conditioning needs obsolete in most climates and very low in more extreme situations. Simply put, Passive Houses keep the total energy needed for heating and cooling extremely low.
The most affordable energy is the not-consummed one
Energy efficiency lies at the heart of the Passive House concept. Over the course of a year, a Passive House building uses no more than the equivalent of 1.5 litres of oil or 1.5 m³ of natural gas (15kWh) to heat each square metre of living space. This can equate to a more than 90 percent reduction in space heating and cooling energy use as compared to consumption in typical building stock. In comparison, a conventional new build still requires 6 to 10 or even more litres of oil per year and square metre of living space, depending on building quality and location.
What is so special about Passive House?
- 1. Exceptionally high levels of insulation
- 2. Well-insulated window frames and glazings
- 3. Thermal bridge free design and construction
- 4. An airtight building envelope
- 5. Ventilation with highly efficient heat or energy recovery
In May 1988, Wolfgang Feist and Bo Adamson asked themselves how buildings could be designed in a more sustainable, energy efficient way. Drawing on this research and with the help of architects Bott and Ridder, Feist went on to build the first Passive House, completed in Darmstadt, Germany in 1991.
In so doing, Feist showed a vision for the future of construction that combined energy efficiency, and thus sustainability, with optimal comfort, affordability, and good indoor air quality. The Darmstadt-Kranichstein terraced house, inhabited by four families, still functions exactly as planned more than two decades later: the measured annual energy consumption has consistently amounted to less than 15 kWh per square metre of living space, year for year.
Over the last two decades, the Passive House Standard has gained rapidly in popularity and has proven to be a reliable approach in an ever increasing range of climates with more than 50,000 units built worldwide according to 2013 estimates. Today, building to the Passive House Standard is not only a sound investment, it simply makes sense.
HERE YOU HAVE THE ANSWERS!
What is passive about a Passive House?
A Passive House requires very little energy to maintain a constant, pleasant temperature. In this sense, such buildings are almost
“passive” as they need hardly any active heating or cooling to stay comfortable year-round. Excellent insulation and highly efficient heat recovery systems make this possible. Passive design principles are well known in engineering as effective strategies to achieve a goal with little to no input. Passive security, passive filters, passive cooling and Passive House are examples of the successful implementation of this idea.
Of course, none of the aforementioned applications are completely passive in the strict sense of the term as they each require a minor amount of input to guide the respective processes along the desired course. The concept is not as much about letting things happen without using any energy, though, as it is about intelligent design: reaching the desired goal with minimal use of complex systems and non-renewable resources.
Why build airtight? Doesn’t a house need to breathe?
The air infiltration through gaps and joints in a conventional building is perceived as draughts. Such “ventilation” is unreliable and uncomfortable. It is also insufficient to ensure healthy indoor air quality on its own, thus necessitating the opening of windows regularly and for extended periods of time. An airtight building envelope ensures that the ventilation system works as efficiently as possible. Perhaps more importantly, it is also key to preventing moisture damage and mould growth: in conventional buildings, gaps in the building structure allow air to pass through and thereby cool down. This can result in condensate that can put the building at risk. Due to the high level of airtightness, this is not a concern in Passive House buildings!
What‘s so special about Passive House windows?
Windows not only allow daylight to enter the rooms, they also make use of the sun’s energy to warm the building. In cool temperate climates, Passive Houses have noble gas filled, triple-glazed window panes with well-insulated frames. During the winter, such high quality windows let more of the sun‘s
thermal energy into the building than they let out. During the warmer months as well as in warmer climates closer to the equator, the sun sits higher in the sky resulting in reduced solar heat gains just when they’re less needed. In most climates, large glazing areas should ideally be oriented towards the equator; windows facing east or west can more easily lead to overheating and provide fewer overall solar gains during the heating period.
Windows need careful planning and, where necessary, appropriate shading. The window specifications needed to achieve the Passive House Standard depend on the local climate conditions.
Can I open the windows in a Passive House?
Of course you can! In a Passive House though, you probably won’t feel the need to do so and it is not necessary throughout most of the year. In conventional buildings, occupants must often open the windows, even if it is particularly cold, windy or wet outside, to tackle stale air as well as odours and moisture arising from used towels, plants and wet clothes among other things. To ensure air quality on par with that of a Passive House, windows in conventional buildings would need to be opened at regular intervals day and night, even during the occupants’ absences. This is simply not feasible and as a result, most homes, schools, and offices are insufficiently ventilated.
Passive Houses are different. The ventilation system provides for high quality indoor air, automatically extracting moisture and thereby clearly improving comfort. The result is a building with no draughts, no cold corners, and a constant supply of fresh air. Fine filters keep dust, pollen, and other particulate materials out, an invaluable advantage for people who suffer from asthma or allergies.
How comfortable are Passive Houses in warm conditions?
A Passive House building’s very well-insulated walls and roof also serve its occupants well in hot summer conditions by keeping the outdoor heat from entering the building. For the windows, shading in the form of external blinds or sunscreens is critical, as it helps keep the heat from the sun outside. In many cases, cross ventilation through opened windows during cooler periods of the day or night can help passively cool the indoor space. Heat recovery is often not needed during the summer months, and most ventilation systems therefore have a summer-bypass, which helps keep indoor temperatures cool through the summer.
Passive House also functions well in hot and humid climates. In such conditions, many of the same general components and passive strategies, optimised for local conditions, are employed. Ventilation with energy recovery effectively reduces heat and humidity inside the building. In areas where active cooling is a necessity, the application of Passive House principles can dramatically reduce cooling needs.