Posts Tagged ‘Passive House’

There’s quite a fraction of people reading this series on LED lighting who will nod their heads in disagreement. You’ve probably heard from your friend’s that they are very-expensive, very-chic, or that LED installations go bonkers after a few months. The problem is not with LED. LED is one of the best lighting options for residences, when used correctly. An inexperienced electrician and incorrect buying decisions can do a lot of harm to the lighting of the house, to you and your pocket. Here’s what to bear in mind:
1. Buy the right type of LED for your requirements. There are low wattage LEDs, which will work on 1mA (very little) of electricity and there are also new High-Power, high wattage LED which will work on more than 1A (100+ mA) and produce over 1000 lumens. The low wattage ones are used singularly to create different effects, usually for decorative purposes. The high wattage ones are used in place of a light bulb, or used in an array to provide enough light for an entire room.
2. Both types of LED lighting have different requirements. Low wattage LEDs burn out very quickly if not used with the right kind of voltage. They require much less than what is available by default in homes. High wattage ones, on the other hand can work with what we have in homes but need adequate heat sinks that will absorb the extra heat they will produce. If heat sinks are damaged, the lighting will burn out in seconds.
3. LEDs are quite affected by ambient room temperature. Installing them into walls which are not properly ventilated or in rooms that tend to get warm affects their life expectancy, causing them to fade out faster.

The main reason we’ve included LED in our recommendations, is because they’re quite eco-friendly, compared to all other options. LED produce much more light per watt of electricity. To be precise they produce around 18-22 lumens per watt, much higher than the incandescent and fluorescent lamps. This means they use less power to produce more, which cumulatively adds up to a lot of energy savings. In fact, the US DOE estimates that if LED lighting were used on a large scale, it would convert to savings of $265 billion, reduce electricity demand for lighting purposes by 33% ; and avoid the set up of 40 power plants across the country.
Also, every time you turn on the lights, you’re contributing to CO2 emissions to the tune of 196 pounds per year, for every light bulb in your house. LED lamps bring this to just 63 pounds every year. LED lighting is also non-toxic, it does not contain mercury like fluorescent lamps and thus recycling them is less hazardous. A few other benefits:
• LEDs are extremely small and are available in different colours. This goes well when you try to get creative with lighting in your house.
• LEDs can be dimmed quite easily. Repeated on-off cycles don’t damage LEDs the way they damage other lights. Thus, using LEDs for Christmas lighting is the ideal option
• They’re shock resistant, not fragile like usual bulbs.

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.

In order to be called as a ‘passive house’ a house must be built with certain standards in mind. These standards were created in Europe and hence apply to homes built in the European countries, but are used more or less in the same manner throughout the world:

1. The house should not consume more than 15kWh/m2 in a year for heating and cooling requirements.
2. Its total energy consumption in a year must not be more than 42kWh/m2

In the US, these standards change a little in the following manner:

A house to be called a passive house must be designed in such a way that it consumes 1 btu per square foot per heating degree day for space heating purposes, compared to traditional homes which use anywhere between 5 to 15 btu. Your contractor should be able to explain better what standards he expects to achieve.

Along with these there are also standards for insulation and air-tightness. The structure should not leak air any more than 0.6 times the volume of the house.

Standards of this type make most people think that achieving them will be rather expensive. However, in the long run, the energy consumption of a passive house is less than 25% than that of a normal house. Plus, the overall cost of building, installing and operating a regular house and a passive house are almost the same.