Posts Tagged ‘Passive solar’

4. Ventilation: Ventilation is properly controlled in a passive house, by means of a mechanical heat recovery ventilator. Although HRV are used in most houses, passive homes use an extremely efficient one, since no other heating or cooling device is used in the house. Most passive houses use both – air to air and earth to air heat recovery systems – depending in the size of the house and climate.

5. Air-tightness: Air-tightness is an extension of the ventilation requirements. Passive houses don’t make use of any HVAC systems – only a HRV system. Thus, it becomes very important that air doesn’t pass through the house in any other way, otherwise, the HRV systems will not be able to perform optimally. Passive houses are therefore super air-tight, much more than conventional houses. The building envelope is sealed thoroughly, and so are any service components that go through it.

6. Space Heating: This is a pretty novel concept in the passivhaus technique. When all the previous measures are not enough to heat a particular house, passive houses use heat generated within the house due to electrical appliances, lights, human beings and animals to heat it. Other than this, some houses install a small or heating device (running on renewable energy) that is integrated with the ventilation system. Some houses also use a micro heat pump that can recover heat from the air escaping through the ventilation system. Together, all these ideas make a conventional heating system quite unnecessary.

7. Electrical Appliances: Passive house use low wattage electrical appliances, CFLs and intelligent installation to minimize the use of electricity.

By using certain principles for building aspects. The passivhaus technique achieves its standards by improving on many aspects of designing and building, particularly:

1. Passive Solar Design: This entails using naturally available sunlight, the suns’ daily and annual cycles to maintain a comfortably warm home without using other heating and ventilation system. This is done by building compact structures, window orientation, using lightweight materials and other techniques.

2. Superinsulation: The walls, floor and roof of a passive house are highly thermal insulated to prevent heat from escaping. Most houses have some form of insulation, however, they will depend on traditional temperature control devices to maintain constant temperatures throughout the house. Passive houses are superinsulated, such that the walls themselves are made up of insulating materials. Because of this, there are no thermal bridges, and there needs to be no external insulation of any kind.

3. Advanced Window Technology: Windows play an important role in designing passive houses. Window placement, size, alignment, material and design help to increase natural lighting in the house without adding to the heat or using electricity. Windows for passivhaus are differently manufactured and are made with extremely thermal resistant. The glass also is generally filled with argon or krypton gas which reduces heat transfer either ways and absorbs UV rays.

We’ve been talking about passivhaus a little too many times in recent posts, and you’ve also probably been wondering about what’s so great about passivhaus. Depending on what kind of research you’ve been doing about building or remodeling you might have come across the term ‘Passive House’. Well, passivhaus is the German term for the same.

Passivhaus is a building technique, or rather a set of building principles which result in creating a house that is extremely efficiently heated and cooled without the need for any external cooling/heating system. To make things simpler – imagine your current expenditure on heating and cooling – in terms of the system/equipment, the energy usage and the maintenance. Now bring this expenditure to almost 10% of its cost – this is what the Passivhaus technique looks at achieving.

Passivhaus achieves such efficiency by the inherent design and plan of the building itself, ambient and incident sunlight and weather conditions like windiness, cloudiness and sunshine. The principles of passivhaus are rigorous and strict ensuring that the structure built is extremely air-tight, optimally utilizes ventilation, super-insulated, and can remain at constant temperatures regardless of outside weather. Most of all – passive houses are sustainable, minimizing usage of energy and creating extremely healthy indoor air quality. Any energy, is required is produced with the help of solar systems – further reducing the carbon footprint and cost.

And contrary to what you might think, passive houses are as normal looking as regular homes and also not as expensive to build as others.

Many of our customers want to shift to solar energy, but find the investment in a solar electric system too heavy. For such individuals, we often recommend going for solar water heaters to take care of the water heating requirements. This is relatively cheaper and easier to install, so you can save the environment and some cash too.

There is a basic difference between solar electric systems and a solar water heater. The former use the light energy of the sun and the latter, use heat energy. Thus, solar water heaters come sans the PV modules but with a solar collector which traps heat instead of light. There are 5 types of solar heaters available in the market:
1. Batch systems: For a 1-2 person household, low cost, temperate climate (not very cold winters), simple.
2. Thermosyphon systems: Passive solar system with no moving parts, suitable for temperate climate, less efficient and more expensive than active solar systems but very reliable, obtrusive in appearance. Fit for 3-4 person household.
3. Open-loop Direct Systems: Active solar system, the most simple of systems, heats domestic water directly in a storage tank, works well in temperate climates
4. Pressurized Glycol Systems: Closed loop system which heats up a non-freezing fluid and uses this fluid to heat up the water, suitable for regions with freezing temperatures,
5. Closed Loop Drainback system: Requires minimum maintenance, Works on similar principle as above, distilled water used as the heat transfer fluid.

Solar water heaters make a lot of financial sense and will drop your electricity bills or heating bills by almost 50%-80%. Add to this tax rebates and credits that you’re entitled to on purchase of a solar heater and the overall cost is reduced by a huge number.

With a solar water heater, the cost is concentrated around the operational costs rather than the fixed cost. While picking a heater, it is a good idea to go figure how much it will cost you to operate each and then compare and pick the best one. The US Dept. of Energy gives you a formula to do this:

365 × 41,045/SEF × Fuel Cost (Btu) = estimated annual cost of operation

Where SEF is Solar Energy Factor – provided by the manufacturer of the heater and fuel cost is the cost of the fuel used to run the auxiliary tank – provided by your local utility provider. The fuel cost could be in British thermal units (Btu) or therms. Once you have this answer, you can compare it with other heating methods and solar heaters.

Installation of the solar water heater will be undertaken by the provider. As with the PV system, you need to ensure that your provider is experienced in installing the type of system you need and is licensed to do so. Since solar water heaters take up some space in and around the house, you will need to check with local building authorities, community laws and also state laws. Your provider should be easily able to install a system that meets all these requirements.

Maintenance of a solar water heater is very important not only to maintain efficiency but also safety. Solar systems are prone to corrosion, freezing and general plumbing issues. Your provider should be able to brief you on issues related to your particular system and also offer periodic inspections. With regular basic cleaning, routine check ups can be held even once in 3-5 years. Generally, opt for a passive system with no moving parts if you wish to minimize maintenance.