What is passive heating and cooling?
In 2010 I decided to build a house using passive solar design principles, so I researched the whole subject from the ground up.
Passive solar building is a modern type of design in which the heating, cooling and ventilation elements are integrated into the design of a building, rather than added later and then hooked up to external energy sources.
Some features of solar passive house design I found too expensive, while some were not really viable, but many ideas were very effective, simple and cheap to incorporate into the building structure.
How does passive solar building design work?
Passive Solar Building Technology needs to take into account the following:
1. How do you keep a Passive House from overheating? Air Temperature
Maintaining a comfortable air temperature is important for human comfort and well-being.
Passive solar design attempts to address this by shading or reflecting sunlight away from rooms that are not used during the day, such as bedrooms, bathrooms and offices, while allowing the sun’s energy to penetrate through windows in the rooms that are used.
By passively controlling your air temperature, you can maximize daytime comfort without interrupting your rest or working throughout the day.
This can be relatively easily done by manually adjusting internal or external screens to maximize the shading effect.
Some building designs have a major part of the structure below ground level, taking advantage of the stable temperatures found there.
2. What is passive lighting?
Adequate light is not only useful for carrying out activities, it also impacts health by helping the body to create vitamin D, regulate mood and dispel moodiness.
It is also necessary for effective human functions such as reading and seeing a computer screen. The trick is to maintain adequate light levels without overheating the room.
Useful devices here are ‘periscope’ type mirrors arranged in a tube that redirect light into any obscure space. Very useful for underground houses.
3. What is the difference between forced and passive ventilation?
Natural ventilation systems play an important role in maintaining acceptable indoor air quality.
Discover your solar saving potential
Without natural ventilation, pollutants such as smoke from cooking and cleaning materials, pollen, dust mites and fungal spores are more likely to build up, resulting in respiratory problems.
As a result of the pollution buildup and lack of fresh air, it’s possible for children or older people to develop chronic diseases such as asthma or hay fever.
The passive solar house circulates air naturally, without expensive conventional mechanical ventilation systems. This allows low-energy heating and cooling of the house to be combined with significant daily fresh air ventilation.
Using natural ventilation features and passive solar heating and lighting to reduce carbon dioxide emissions helps to build a sustainable home.
4. How much energy does a Passive House save? Energy Saving
Saving the planet’s resources is important to all building users. Modern passive design uses much less energy than conventional buildings, resulting in less pollution and cost savings.
The best passive designs consume between 6% to 10% of the energy needed by a conventional home.
In addition, a well-insulated home keeps the thermostat at an even lower temperature, allowing the comfort level to be maintained for longer.
When considering efficiency and cost savings, it is easier to come to the conclusion that an energy efficient passive house is better for your wallet and the planet.
5. How do you control humidity in a passive house?
Human humidity levels are important for health. If humidity and temperature increase beyond a critical level, then we become ill.
To avoid this situation, it is important to manage humidity levels and heat levels within a home to maintain comfortable living conditions. Raised floors can assist in the management of humidity by circulating the air through different planes of the building.
Introducing cool moist air in summer can also create a comfortable home environment. By pushing warm moist air out of the house in summer, the air will be replaced by cool dry air, ensuring comfortable living conditions.
Bringing air in from drainage pipes buried underground will introduce air of a constant temperature and humidity, cooling in summer and warming in winter.
6. What is a passive heating system?
Intelligent building design can go a long way towards energy free heating in the winter. The key to efficient heating design is maximizing the amount of heat energy available from the sun and also from the ground.
Simple designs ensure that the sun’s energy can be absorbed without overheating in daytime and then gradually released at night-time.
7. Cooling – How do you keep a passive house cool?
One of the major problems with passive solar design is that it can make homes uncomfortably hot in summer and may not be suitable for tropical climates or those with no annual variation in temperature.
Solar air conditioning can also be used to incorporate cooling into the passive solar design. These are viable in various forms but don’t help in hot humid nights.
In this case, pulling air in from underground is the favorable solution.
Important passive solar design features
Passive design needs to come up with solutions to satisfy the requirements of the precious 7 features described above.
There are two criteria:
1. No external energy should be needed
Passive solar house design doesn’t supply energy from an external source like an air conditioner. The energy comes from the sun’s light, heat and wind.
Heat or cooling extracted from the ground is considered in the same category, as in reality, all energy comes from the sun.
2. The solutions should be part of the building fabric
As a result, any elements that are used in the building should be part of the fabric of the building, rather than amendments or additional features. This keeps the construction cost down and ensures that they will last for many years to come.
How can passive solar design be warm in the winter and cool in the summer?
One example of a passive building feature that gives cooling in summer and heating in winter is the solar wall. This incorporates a solar mass which stores energy like a battery in the day and releases it slowly at night.
As a cooling medium, the solar wall can cool down at night-time and maintain a lower temperature in the room.
How does a passive solar heating system work?
Passive solar heating systems maximize the energy from the sun’s rays that enter the building. A passive thermal water collector can also introduce warm water into the home to heat the interior.
How do passive solar panels work?
Passive solar panels don’t need external energy to operate pumps for them to circulate hot water. The water circulates according to thermosyphon principles, which naturally regulates the temperature.
When the water is hot, it transfers heat to the water mass storage or building interior. When the temperature of the water falls, it stops circulating.
A hybrid solar panel may have a PV element that can operate a small water circulating pump when the sun shines and the water temperature rises enough to provided useful heat.
How is passive solar energy stored?
Passive solar heat is stored in any large mass, such as earth, concrete of water. Concrete is not favored as it is a pollutant.
A common approach is to construct the South-facing wall of the passive solar house out of oil-barrels filled with water.
The water stores energy during the day, when the interior is shielded from the heat, and can be released gradually at nigh-time.
Why is passive solar design better for the environment?
Passive solar design represents a huge reduction in home energy use, hence the amount of precious resources needed. The small amount of energy need can be provided by solar electric PV or wind.
Examples of passive solar design
Rural home builders in many countries have used traditional passive building techniques for generations to good effect:
- Small windows stop the heat of the day coming in while limiting the amount of heat loss at night
- Thick walls provided insulation against overheating and heat loss
- Natural clay plaster also reduces heat transfer
- Thatched roofs and vegetal roofs keep out the fierce sun and also holds in the warmth at night.
- A wide terrace roof allows the weak low-angled winter sun’s ray’s into a house while blocking the intense heat of the higher-angled summer sun’s rays.
A method of underground cooling
A widely used method involves sinking large-diameter PVC pipes up to 2 meters underground, where the temperature is a constant 8 degrees C.
A simple and silent bathroom extractor fan pulls air the pipe inlet out in the yard and into the house, providing cooler are in summer and warmer air in winter.
Are passive houses worth it?
The main savings are of course in energy consumption, which can be up to 90%, but there are other considerations.
It’s a different way of living with more awareness instead of just consuming with no thought for the consequences. Whichever way you look at it, passive houses are worth the cost and the effort.
What type of house is the cheapest to build?
Tiny houses are the cheapest to build, simply because they use much less materials than a standard-size home – up to 75% less!
If I were building a passive home, then I would go for an underground variety. It reduces the construction materials needed and has very stable heat controls built-in due to the huge thermal mass all around you.
Can you make your house a passive house?
You can, but IMO it would be too expensive to retrofit a normal house into a passive solar home. It would never be as efficient as building from scratch