What Is a Passive House?

Passive houses are very well insulated, virtually airtight, buildings which minimize energy loss and improve occupant comfort. Passive house design considers the entire life-cycle of the building and uses a variety of 'passive' building solutions to eliminate conventional 'active' technologies that consume wasteful fossil fuels.

Passive Solar Design

Passive solar design is specifically used to exploit free energy from the sun, to provide warmth. A passive house is orientated so that large south facing windows absorb energy from the sun. The rooms are laid out so that the solar heat is distributed from these windows through the interior of the home. The process of capturing the solar energy is considered to be 'passive', since the building does not generate the energy itself. The heat energy comes from a natural source and is not generated exclusively by artificial means.

Provide Thermal Mass

Passive house buildings can be constructed from either dense or lightweight materials. In the case of lightweight construction, like timber frame, some internal thermal mass is incorporated. Thermal mass allows dense construction materials, typically concrete, stone, brick or tile, to store the free heat. During the day, when external temperatures are highest, a large thermal mass inside the insulated envelope will absorb the sun's heat. When the external temperature cools down in the evening, the thermal mass will naturally radiate that absorbed heat throughout the rooms.

Install Super Insulation

Insulating the building envelope is one of the most important passive house measures as it has the greatest impact on energy expenditure. In the average house, well considered and expertly installed insulation can reduce the amount of heat lost through the building envelope, by at least half. In addition, a high standard of thermal insulation will considerably improve thermal comfort for the building occupants.

Make the Building Airtight

Effective airtightness is another important contributor to passive house design. Warm air leaking from the building is a major cause of heat loss, which results in wasted energy. Improving the building's airtightness reduces the uncontrolled air flow through gaps and cracks in the building fabric and must be addressed by the designer early in the planning process.

Fit Triple Glazed Windows

High performance windows are a key contributor to the overall efficiency of the building envelope, as they are manufactured to deliver high thermal values. In passive house buildings, it is usual to combine triple-pane insulated glazing, low emissivity (low-E) glass and argon or krypton filled air gaps. Expertly designed and installed triple glazed windows will significantly reduce energy usage and improve occupant comfort.

Make Use of Waste Heat

In addition to using passive solar heating, passive houses make use of the waste heat from lighting, domestic appliances like refrigerators and washing machines, and the body-heat from the occupants of the building.

Install Heat Recovery Ventilation

Heat recovery ventilation is the process of exchanging heat energy contained in the air which is extracted from a house and transferring it to the incoming replacement air. This system can comprise either a central extract system or individual room fans. Although this ventilation method is an 'active' technology, using a small amount of electricity, it is considered to be a worthwhile contributor to energy saving. It provides the building with essential fresh air, improves occupant comfort and conserves the building's heat.

Fit Renewable Energy Heating

An underlying objective of solar passive design is the desire to dispense with conventional heating systems altogether. It is usually necessary to provide some supplementary space heating to maintain comfortable conditions on particularly cold winter days. Often this can be achieved via the low volume heat recovery ventilation system that is provided to maintain air quality. As an alternative to this, a renewable energy technology like a wood burning stove, solar heating, air source heat pumps or ground source heat pumps, may be preferred.

For more information on passive house design visit www.EcoFriendlyBuilding.com

David Stoppard is the Editor of http://www.lowenergyhouse.com/ and a group of associated websites that deal with the issues surrounding eco-friendly building. The LowEnergyHouse.com websites have evolved from an architectural practice with a keen interest in energy conscious design. Its members have set out to promote energy saving measures, sustainability and renewable energy technology in building, in order to help, protect the environment, secure future energy supplies and reduce fuel poverty.

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Passive Solar Techniques - The Trombe Wall

Mention solar technology and most people automatically assume that solar panels are involved in one way or another. While this is generally true, the concept of passive solar energy has been used from thousands of years to heat structures. The trombe wall is one form of low tech used in passive solar for heating a home at night.

The trombe wall is named after Felix Trombe, a French inventor who created the modern version in the 1950s. The basic idea behind the wall is the manipulation of thermal storage and heat release. Put in simpler terms, the wall is used to capture and hold heat during the day and release it in the evening. In doing so, the wall becomes a repository for heat much like the pavement on a parking lot during the day.

To understand how the trombe wall functions, it helps to first contemplate how passive solar energy works as a heating process. A simple example suffices. Imagine you drive to the grocery store. You park in the parking lot and head inside. You are there for no more than 30 minutes. When you come out to the car, what has happened? It has turned into an oven! This is passive solar at its finest. The sunlifht has heated up every dark surface in the interior of the car, which then radiates heat. During the summer, sitting down on the seats can be a delicate maneuver, particularly if you are in shorts!

What if you could capture this heat during the hottest periods of the day and slowly release it at night when temperatures drop? This is exactly what the trombe wall is designed to do. The average trombe wall is between 8 and 16 inches thick. It is typically made of concrete. On the exterior face, the wall is covered with a heat absorbing material. This can be a painted on dark color or absorbent material. A double layer of glass is then placed about an inch outside of this and forms the exterior of the structure. It looks a little odd to have a wall inside of glass, but the heating impact is significant.

As sunlight penetrates the glass, it heats up the surface of the concrete wall. The wall then absorbs the heat at a rate of about an inch an hour. By the end of a sunny day, you have a concrete wall that is heated up much like the rocks in a sauna, although obviously not as hot. The double glass serves to insulate one side of the wall. Once the temperature in the area starts to cool below the heat level of the trombe wall, it will start to emit heat. The heat rises. Vents and small fans can be put in to circulate the warm air into the interior of the home where it can be funneled to rooms in use. This can be done day-after-day so long as the sun hits the wall.

Solar power is a complex energy platform and involves much broader techniques then just solar panels or water heaters. Passive solar can be a powerful way to deal with heating issues and the trombe wall is one example of this.

Thomas Ajava writes for SolarCompanies.com - your online source for information on solar energy such as solar farm residential developments.

Original article

Home Systems: Active Vs Passive Solar Heating Systems

Are you interested in using a solar heating system? If so, then you will have several options. One of the main ones is whether to choose an active or passive system.

What are Active Solar Heating Systems?

This type of system involves harnessing and storing (in the form of heat) solar energy. It uses fans and other objects to dispense heat that has been harnessed. Solar cells constructed of silicon are the most common type of solar heat collectors. Typically, the cells are contained on solar panels, which are located on the roof of a home.

What are its main types?

There are two primary types. Their difference lies in the material that captures and moves the heat that is located in the solar collector. Usually the material is a gas or a liquid. For instance, an air-based system usually involves transpired air collectors or air room heaters. On the other hand, liquid-based systems usually involve water (or antifreeze) to capture and move heat.

How much power does it provide?

Usually the goal of such systems is to heat up to three-fourths of a home's interior. When more solar energy than a house needs is produced, the homeowner could then sell excess power back to his or her local utility company. Also, it is advisable to heat both the air and water in your home, so your system can function throughout the entire year.

What Are Passive Solar Heating Systems?

This type of system is a low-technology method of capturing solar energy. It functions by directly capturing the sun's warmth, and then retaining it within the house for the function of heating. This is mainly achieved through methods such as quality insulation and windows. This type of system can lower your current heating costs, or even replace your home's current system.

What are its components?

Windows are the primary components of such systems. The goal is to maximize the amount of sunlight and heat that one can collect during the daytime. Typically, the windows consist of a special variety of glass that absorbs as much heat as possible-and then keeps it indoors for a maximum amount of time.

Besides windows, another common component of Passive Solar Heating Systems are trombes, which are a special type of wall. There is a pane of glass in front of the wall. The mission is for the space between the glass and wall to collect heat. Another method is to paint the concrete walls black, so they will absorb sunlight more.

What are its benefits?

This is generally an ideal option when you are looking for a solar heating system for a new home. The reason is that Passive Solar Heating systems are based on factors such as the location of the windows in the home, the location of the building itself, the amount of insulation in the building, and so on. These issues can be quite challenging to change within existing homes-and especially the location of the home!

After learning the basics of Active and Passive Solar Heating Systems, it is time to determine which one is best for you.

Original article