The Technology Context – B101

How do Zero Energy Homes Help the Environment?

Fossil-fuelled electric power generating plants cause more air pollution than cars, and they are a major source of the greenhouse gases that have led to global warming. Therefore it is becoming increasingly important that we find an alternative power source, not only because fossil-fuels cause pollution but also because they will soon run out so it is to everyone's benefit that we switch to renewable resources as soon as possible.

A Zero Energy Home (ZEH) is one such solution as it is a house which generates just as much energy as it consumes. It is just like a typical home in the sense that it is connected to, and uses energy from, the local electric utility. But unlike typical homes, at times the ZEH makes enough power to send some back to the utility grid. Over the course of a year a ZEH produces enough energy to result in a power bill with a net total of 0.

The definition of a ZEH is “a residential or commercial building with greatly reduced needs for energy through efficiency gains, with the balance of energy needs supplied by renewable technologies.” A ZEH combines state-of-the-art, highly energy-efficient designs and equipment with on-site renewable energy generation. This typically includes a solar hot water production system and a rooftop Photovoltaic Cell system. Zero Energy Homes are designed to perform well, be comfortable, require only standard maintenance, and look no different from an ordinary home as the picture below shows.



As mentioned above ZEHs make use of Photovoltaic Cells, these are placed on the roof and convert sunlight into electricity. An obvious benefit to a potential buyer of a ZEH is the thought of powering everything in the house for free. But although the cost of Photovoltaic cells has fallen greatly over the last 30 years they still remain quite pricey. As well as the cells the houses also need to be installed with an inverter to convert the DC current produced by the Photovoltaic Cells to AC current, (shown by the picture below) which is used by most household appliances. The cost of implementing these necessities is greater than the potential savings on the annual power bill.



On certain days, such as cloudy days, night time, etc, the Photovoltaic cells are not going to produce as much energy as is needed to power the house. On these days the homeowner purchases the excess electricity needed from the grid. On sunny days when the cells are producing more energy than the house is using, the grid buys the electricity back off of the homeowner causing the meter to run backwards.

If the cost of the Photovoltaic Cells were low enough there would undoubtedly be far more people interested. Judging by the trend in prices of Photovoltaic cells it will not be long before ZEHs start becoming fairly common and i believe that this will make a big positive impact on the environment.

Personal Relevance
I consider this subject personally relevant to me because i enjoy the design of architecture and feel strongly about the environment. Therefore this topic seems suited to me as it brings both of these aspects together.

Plan of Inquiry
To find out more about this subject i will conduct further research such as targeting a company which specialise in ZEHs and finding out their corporate policies. I also plan on e-mailing them with several questions such as, "What locations have you constructed in?" and "how many houses have you built to date?"
I will also try to obtain statistics which compare ZEHs to a standard house in terms of features such as energy effiency.