The Technology Context – B101

How are Zero Energy Homes both environmentally friendly and beneficial to the occupier?

An existing project that appears to have met the criteria of creating a series of Zero Energy Homes that are both environmentally friendly and suitable for a comfortable, cost efficient family home is Pardee Homes, California. The homes they have designed are said to save at least 60% of energy costs per year and roughly use 15% less energy than the standard home in California. The first home built by Pardee was in 2001, with approximately 3000 homes being built in the last year.
Pardee gained information from the ConSol Company’s comfortwise program on what was needed in terms of mechanical systems, insulation and design to make their homes greener. From this, Pardee established the LivingSmart options. These included EnergySmart to reduce energy consumption, EarthSmart to conserve resources and use recyclable or sustainable materials and HeathSmart which focussed on healthier indoor air and water quality. They placed individual logos to identify these features throughout the house.
One of the main features of a Pardee Zero Energy Home is spectrally selective Low E glass for the windows which has a microscopic coating that allows selected portions of the solar spectrum to pass through whilst restricting others. This lower amount of solar heat being emitted will keep certain homes warmer in the winter and others cooler in the summer, dependant on the climate. There are different types of Low E glass to suit varying climates for example Moderate Solar Gain Low E windows would restrict a selected amount of the suns heat in summer but allow a good amount in winter, whilst Low Solar Gain Low E windows would screen out most of the heat from the sun at all times, usually used in much hotter climates. Not only are these cost efficient and useful for setting a comfortable climate in the home they also prevent fading of household artefacts like carpets and artwork.
Another energy conserving feature used in Pardee Homes is the sealed duct systems. The benefits of these include keeping rooms warmer in the winter and cooler in the summer, improving air quality by reducing the amount of pollutants (such as fumes from garden chemicals and dust particles) entering the home and protecting the environment, as energy used in the home comes from burning fossil fuels at power plants, contributing to smog, acid rain and global warming. Sealing the ducts and reducing the amount of energy required to heat or cool the home can reduce the amount of air pollution generated. A similar solution to this is Cellulose attic insulation which also contributes to reducing energy loss.
Additional features used in Pardee Homes include photovoltaic cells that generate electricity directly from sunlight, engineered and certified wood to help protect forests, low VOC paint and a central vacuum system that is good for the air, as well as fluorescent lighting which is 75% more energy efficient than standard lighting. In the last year the WaterSmart feature was also added to the program. This included drought tolerant landscaping, drought resistant plants, water saving faucets and fixtures and multi programmable irrigation clocks that water the garden according to needs to avoid over watering. Meters are installed in all the houses to tell the occupants exactly how much energy is being produced and how much is being used.
Last year Pardee homes appeared on 'Extreme Makeover Home Edition' to demonstrate one of their Zero Energy Homes. The 4278 square foot home included a 3.0 kilowatt roof - integrated solar generated power system as well as many of the other energy saving features listed above. The electrical demand of the home was reduced by 73% taking the energy usage down from 1080 kW per month to just 300.

Political Effects
The Californian government appear to be greatly in favour of the increase of Zero Energy Homes, and have given a large amount of money to the research for development of photovoltaic cells. There has also been the introduction of collaborative government demonstration projects such as the super insulated houses Saskatchewan house and Leger house. Saskatchewan house was built by the Canadian Government and was the first house to publicly demonstrate the environmental and economic value of super insulation. Leger house was built in 1979 and had a more conventional appearance than Saskatchewan house. The publicity of these government houses influenced and inspired other builders, and many more super insulated houses were built over the next few years. Although general interest in super insulation has declined as energy prices fell, a large number of U.S builders now use more insulation than would be necessary for the typical 2x4 stud wall either by using 2x6 studs or by adding rigid foam to the outside of the wall. Few of these houses would qualify as super insulated but they still make a great difference in regards to energy reduction. The pictures below show the Saskatchewan house on the left and a diagram of how super insulation functions on the right.

Lastly from a more negative political viewpoint, due to this wide acceptance of zero energy homes more government incentives or building code regulations are required, as well as development of recognised standards or significant increase in the cost of conventional energy, due to the fact that as Zero Energy homes become more common, people will become less obliged to use human produced energy that is both more expensive and damaging to the environment, causing conventional energy companies to be in danger of going out of business.

Financial Effects
From a financial viewpoint, there have been a lot of negative opinions relating to Zero Energy Homes. For example builders have to be trained in order for them to incorporate Zero Energy Homes into their general building practise, and sales staff will need to be advised on the benefits of zero energy homes in order to sell them adequately. This excessive amount of training will cost time as well as money. Also, builders tend to be sceptical about homeowners willingness to pay the expensive up front cost of a Zero Energy Home even if the money saved on energy reduction would mean it would work out cheaper long term.

One feature of a zero energy home that is particularly financially beneficial is the reduced necessity of air conditioning. Zero Energy Homes have a 3ft overhang as opposed to the 1.5 ft of the standard home this produces twice as much shade and is beneficial for controlling the heat build up on the walls and windows. The reflective white tile roof instead of the typical grey/brown asphalt shingles of a normal home also reduce the temperature of the home, as on a day of peak climate the attic temperature of the standard home reached a maximum of 138 degrees Fahrenheit, whilst the Zero Energy home remained at 100 degrees Fahrenheit, the same as the outside air. Other factors include exterior insulation which thermally encases the masonry of the house meaning it will be pre-cooled during the day when the sun is at it's brightest maintaining indoor comfort into the evening; as well as a programmable thermostat which means the indoor temperature increases at night or when the house is unoccupied, so the house cools to a comfortable climate when the house is in use. These features decrease the need for air conditioning, reducing energy consumption therefore lowering the utility cost. Finally, this results in the Zero Energy Homes requiring an air conditioning system only half the size of the one used in the typical home, as well as the usage being greatly reduced.
Zero Energy Homes use only 18% of the energy costs of a normal home, as shown in the table below:

The pie chart below demonstrates the listed cost efficient factors applied to the amount of energy usage reduced.

To conclude, Zero Energy Homes are beneficial to both the home occupier and the environment due to a number of factors. The reduced energy usage in Zero Energy Homes results in them being much more cost effective than the standard home, as well as options such as Low E glass helping controlling the climate of the home, and sealed ducts reducing the amount of pollutants in the air causing the home to be a generally healthier and more comfortable place to live. The recycling of electricity managed by photovoltaic cells means that the use of fossil fuels is greatly reduced helping to prevent environmental issues such as air pollution and acid raid. Pardee Homes WaterSmart feature is also greatly beneficial due to the fact that the programmable irrigation clocks mean that less wastage of water is concerned and the occupants of the homes are generally protected from drought. The water in Zero Energy Homes is also much cleaner, healthier and free of 99% of impurities found in standard tap water.

Bibliography
(2008, January 14th) Nations building news online for April 4, 2005
http://www.nbnnews.com/NBN/issues/2005-04-04/Front+Page/3.html

(2008, January 14th) Zero-Energy Building – Wikipedia, the free encyclopaedia
http://en.wikipedia.org/wiki/Zero_energy_building

(2008, January 14th) The Potential Impact of Zero Energy Homes
http://www.toolbase.org/PDF/CaseStudies/ZEHPotentialImpact.pdf

(2008, January 14th) On the Path to Zero Energy Homes
http://www.eere.energy.gov/buildings/building_america/pdfs/29915_zeb_path.pdf