What is an Electric Vehicle?

Electric vehicles are propelled by an electric motor (or motors) powered by rechargeable battery packs. The batteries transfer energy to an electric motor, the motor turns the drive train that turns the wheels. It is a highly efficient technology; up to 80% of the energy in the battery is transfered directly to power the car. Everything is computer controlled and a display shows you how the car is performing. The display lets you know about how much battery power you have left, and if you need to find a place to recharge, you can use the software built into the car or on your mobile device to guide you to the nearest charge point. When you are ready to charge your EV’s battery, instead of a gas tank, there is a power cord, and instead of refueling, you recharge: just plug it in.

Benefits of electric vehicles

Electric vehicles are quickly gaining popularity and for a good reason, Besides being good for the environment by keeping our air clean, they are also convenient, sleek and quiet, and for most of the short distance driving we do, they are the perfect way to get from point A to point B, safely, reliably, and comfortably.

Consider the following advantages of EV’s over internal combustion engines (ICE’s)

1. Energy Efficient. Electric motors convert 75% of the chemical energy from the batteries to power the wheels. In comparison, internal combustion engines (ICEs) only convert 20% of the energy stored in gasoline.

2. Environmentally friendly. EVs emit no tailpipe pollutants, although the power plant producing the electricity may emit them. Moreover, electricity from nuclear-, hydro-, solar-, or wind-powered plants causes no air pollutants.

3. Reduce energy dependence. Electricity is a domestic energy source, and by using EV’s we are reducing our dependance on foreign oil as a nation.

4. Performance benefits. Electric motors provide quiet, smooth operation, stronger acceleration and require overall less maintenance than ICEs.

5. Tax Incentive. The US government is supporting a more wide-spread use of EV’s by providing special tax credits. Electric vehicles purchased in or after 2010 may be eligible for a federal income tax credit of up to $7,500. The credit amount will vary based on the capacity of the battery used to fuel the vehicle.

Disadvantages of electric vehicles

Some of the main drawbacks of EVs are battery related challenges and our outlined below. Yet most of these issues can be resolved with a little extra planning on the part of the consumer.

1. Driving range. Most EVs can only go about 100–200 miles before recharging, where as gasoline vehicles can go over 300 miles before refueling. While this is an issue, taking a look at the statistics reveals a different perspective. As it turns out, more than 80 % of Americans drive less then 40 miles round trip for their daily commute (US Department of Energy), which is just right for an EV.

2. Recharge time. Fully recharging the battery pack can take 4 to 8 hours. Even a “quick charge” to 80% capacity can take 30 min. This issue can be taken care of by recharging overnight, when they are done driving for the day, and electricity may be cheaper. However, for a quick charge during the day, charging stations are popping everywhere in convenient community locations across the US. Another option that is available on the market is an extended range EV: it starts by using battery power, but when the battery power runs low, gasoline fueled engine kicks in to power the electric motor, which in turn drives the wheels. So for shorter trips, you can rely on electricity, and still take longer road trips whenever you want. Anywhere you go, you can simply plug in or fill up.

3. Battery Cost and Weight Currently, the large battery packs are expensive and may need to be replaced one or more times. They are also heavy and take up considerable vehicle space. However, battery technology continues to advance, and researchers are working on improved battery technologies to increase driving range and decrease recharging time, weight, and cost.

Overall, with the speed of technological advancements in the car industry, it will not be long before electric vehicles will become totally compatible with internal combustion engine cars, while boasting major personal and environmental advantages. As Americans we have had a long love affair with cars, often choosing power and speed over preserving our environment. However, as a society we have started to turn the page, as more of us make a conscious decision to opt for clean, comfortable electric vehicles.

How Geothermal Heat Pump works:

Here is how it works: bury a loop of pipes, called a heat exchanger just below the surface, and fill them with water, or water and any free solution. During the winter months, the air is usually cooler than the temperature below ground. The solution circulates in a loop underground and absorbs the earth’s heat. This heat is brought to the surface and transferred to a heat pump. The geothermal heat pump warms the air and then your regular heating system warms the air some more to accommodate a comfortable temperature. Finally, ducts circulate the air to the various rooms. A huge benefit is that the geothermal system does not have to work as hard to make people inside comfortably warm, and you save a lot of money on your heating bill.

In the summer time, the geothermal heating and cooling system works in reverse: when its hot outside, the temperature below the surface is cooler than the summer heat. The fluid in the loop absorbs heat in the building and sends it underground. The ground’s lower temperature cools it and it circulates again and again. Now you are saving money on air conditioning. Buildings with large parking longs that use huge geothermal heat pumps to heat and cool the building, can have the system spread out its loop horizontally under the parking lot. However, buildings and homes that do not have all that extra space, can go straight down and use a vertical loop system instead.

Efficiency of geothermal heat pumps:

Getting right down to the bottom line, GHPs use 25%–50% less electricity than conventional heating or cooling systems. This translates into a GHP using one unit of electricity to move three units of heat from the earth. According to the EPA, geothermal energy heat pumps can reduce energy consumption—and corresponding emissions—up to 44% compared to air-source heat pumps and up to 72% compared to electric resistance heating with standard air-conditioning equipment. Geothermal heat pumps also improve humidity control by maintaining about 50% relative indoor humidity, making them highly effective in humid areas. Even though the installation price of a geothermal heating and cooling system can be several times that of an air-source system of the same heating and cooling capacity, the additional costs are returned to you in energy savings in 5–10 years.

Moreover, geothermal heat pump systems have few moving parts, which are housed inside a building, making them highly durable and reliable. The underground piping often carries warranties of 25–50 years, and the heat pumps often last 20 years or more. All the components of the system are easily accessible, which increases the convenience factor and helps ensure that the upkeep is done in a timely fashion. Also, since geothermal pumps (ground source heat pump) have no outside condensing units like air conditioners, there’s no concern about noise outside the home. A two-speed GHP system is so quiet inside a house that users do not know it is operating: there are no tell-tale blasts of cold or hot air.

Another important benefit is that geothermal heat pump systems allow for design flexibility. This means that they can be installed in both new and retrofit spaces. Because the hardware requires less space than the amount required by conventional HVAC systems, the equipment rooms can be reduced in size,freeing space for productive use. GHP systems also provide excellent “zone” space conditioning, where different parts of the building can be heated or cooled to different temperatures. Attesting to the system’s effectiveness, there are approximately 50,000 geothermal heating systems installed in the United States each year, and the number continues to grow as more consumers learn about the benefits of geothermal heat pumps.

Geothermal heat pumps can be used just about anywhere in the US, because all areas have nearly constant shallow ground temperature, although systems in different locations will have varying degrees of efficiency and cost savings. The constant temperature of the earth, just below our feet is a sustainable resource, literally in our own back yard. Geothermal energy is a clean energy source ready for us to use, to heat and cool our homes and offices while lowering our utility bills.

How geothermal heating and cooling works:

A geothermal heat system uses a geothermal heat pump and a ground source heat exchanger to extract the earth’s thermal energy and combine it with thermal energy produced by the heat pump itself, to increase efficiency. The ground temperature below the freeze zone (about 6 feet below ground) is constantly at about 55-60 degrees Fahrenheit, which means in the summer it is way below the ambient temperature, and in the winter its way above the outside temperature. By combining geothermal energy with the thermal energy  produced by the geothermal heat pump, you achieve the efficiency of about 3 times more than a conventional heating or cooling system.

In a nutshell, here is the very basic setup of a geothermal heating and cooling system: A ground source heat exchanger is buried into the ground – either as loops in a trench of 6-9 feet deep, or into a bore hole or a well of 300-500 feet deep. A heat exchanger can also be placed in a large enough body of water, but this and other setups are not as common, so we will skip them for now.

The water pump circulates the heat exchange liquid (a form of antifreeze) through the ground source heat exchanger loops, bringing the geothermal energy to the heat exchanger inside a  geothermal heat pump. Meanwhile, a heat pump (which essentially works as an Air Conditioner, but in forward and reverse modes) produces the needed hot or cold air, which is combined in the heat exchanger with the earth thermal energy, and then delivered through air ducts to your living room or bedroom.

How heat pump works:

The video above demonstrates the the basic principal of heat pump operation, which is essentially a dual mode air conditioner.

Heat pump operates on principle when the gas is compressed, it releases heat, and when it is decompressed, it releases cold.

So I’ll let the big guys do their things, while I tell you about the event, which so many people waited 2+ years for, and worked so hard to make it happen – ladies and gentlemen – Solar Decathlon 2009!

This was our first Solar Decathlon, but certainly not the last. Since we were sponsors of Team Boston Solar Home, most of my coverage will be focused on it. However, there were many great solar homes this year: Team California and Team Germany were battling for first place (you can see Team Germany solar home in the picture above – a black house, second from the right).

As I wondered through the Mall, looking at these homes and being hesitant to stand in line to see very similar interior set-ups, my main focus was on the outside. Solar technologies, energy efficiency and exterior design were my main concern, as these factors make a true solar home, while the inside can always be remodeled.

Team Boston Solar Home:

As a future architecture student, and a “construction worker” now, I look at these houses with a slightly different perspective than most people. For me, the ease of construction, most energy efficiency and reasonable cost are the most important things, followed by a nice design. Unfortunately, many of the innovative approaches used for this competition, are not accessible to the masses, and remain to be a privilege for the most extravagant home buyers with deep pockets. While I have no problem with it in general, in my opinion, the purpose of a Solar Decathlon is to move innovative green building technologies into the mass housing market, so that such technologies would actually make a major difference in improving the environment and reducing CO2 emissions.

It is expected of all these homes to be super insulated and have solar PV panels on their roof. I was interested in innovative new approaches at achieving maximum effect (energy efficiency or energy generation) using the least expensive methods. In this regard, the Boston Solar home has (had) great potential, if not for the massive glass array on the northern side of the house. All these windows and doors will let all the heat escape in the winter, which makes it that much less efficient. This is a fixable situation however – just remove most windows and put a wall there

Despite potential heat loss, the liquid-filled glass units on the southern side of the house will collect tremendous amounts of solar heat and store it, making it much easier to heat this house. Find out more about these liquid-filled solar thermal windows and wall panels.

In addition to solar thermal wall panels, Boston solar home has about 6.4 KW solar pv system on the roof and a solar thermal hot water heater, for heating and domestic use. There are many other new and innovative design features used by BAC (Boston Architecture College) and Tufts University students in the construction of this home – too many to list here. You may check out the project’s website – www.livecurio.us.

Team Spain solar home:

Another solar homes that attracted my attention was the one build by Team Spain (which for some reason was doing VERY poorly in this competition).

Apparently, these bi-pv cells are very good at capturing indirect sunlight and help the house generate the most electricity it possibly can.

Team Spain used a very interesting )in my opinion) approach at capturing ALL available solar energy with their powerful solar PV array. This roof mounted array can rotate at the center, following the sun going across the sky, thus always keeping the most efficient angle of the PV panel to the sun. It is basically a gigantic solar tracking system, which is however complicated and expensive systems to implement, which make this house not as competitive in terms of costs and ease of building.

Additionally, the glass walls of this home have integrated solar PV cells, which captures even more solar energy. It is a good idea, but and overkill in my opinion, and the roof mounted solar system should be more than sufficient and, unless they used “dummy” cells on east, west and north sides of the house, it is a waste of solar capacity, as the sun will barely or never hit those solar cells.

Cornell University Solar Home:

Another interesting design, which for some reason reminded me of the Water World movie was a solar home built by Cornell University students. It featured three round “rooms” connected to each other, and a large solar PV system, which for some reason was mounted flat to the ground.

It may not be the best designed house (in terms of competition rankings), and round rooms make it ever more difficult to build, but the steel frame and a VERY cool vintage design made it very attractive. As I was writing this, Cornell’s solar home was in 6th overall place, with a few more contests to go. You can view current team rankings here: http://www.solardecathlon.org/scoring/

As a side note, as of Oct. 13th, Team Boston solar home is in 12th position and Team Spain is in 18th place, while 1st place belongs to Team California.

Let the best solar house win!

The Solar Decathlon will continue for another week or so, and there are a lot of contests left in which either team can pull forward dramatically. Therefore, I will not even try to predict the winner. All houses presented in the Solar Village this year were very well designed and built, and the green building technologies used in them will in the (hopefully) near future migrate into traditional construction markets and help home and building owners reduce the over all energy use and make our environment better. This competition is also an inspiration for the new wave of architects who will be literally building our future homes and infrastructure, and as you can see, they all have great ideas. I will continue the cover the Solar Decathlon 2009 in future posts, and soon you will be able to review the IB flat roof installation which we did on the Curio Home – look forward to seeing it soon on our cool roofing blog.

In 2007 Solar Decathlon, Boston was represented by a Solar Home built by the MIT team and many volunteers interested in green technologies. This year it is Boston Architecture College and Tufts University that sponsor the solar home built by Team Boston. Why team Boston? Because many folks that participated in the 2007 Solar Decathlon are doing it again.

We and IB Roof Systems (the manufacturer of Cool PVC flat roofing membrane) had our own humble involvement by sponsoring the roof installation on top of this amazing creation of the latest architectural designs and green construction technologies. Now, with a new IB 50-mil PVC membrane, this solar home will be completely water-tight and the built in water collection system will provide it with as much H2O as needed. The roof is also very well insulated with over 5 inches if rigid ISO tapered insulation and additional 12 inches of insulation between the rafters. The cool roofing properties of IB Roofs will minimize its cooling needs, and will waterproof the entire building. Hopefully everyone will be eventually replacing their old black roofs with cool roofs such as IB. Also, when roof removal is required by code, calling a skip hire to remove the old material, and then installing these new highly efficient roofs is an economical and sustainable way to deal with roof tear-off. In some cases, the old asphalt roof can be recycled and used in synthetic roofing products.

About the Team Boston Solar Home:

By definition, a solar decathlon project will use different solar technologies available on the market. Team Boston has created such a design where virtually every solar system has been be utilized. There will be a 4.6 KW Solar PV system consisting of 20 SunTech PV panels. There will be a large solar hot water installation using Viessmann Solar Thermal hot water panels and water storage unit. But aside from these common, roof mounted solar systems, there will be a new solar thermal system, that will provide up to 70% of FREE heating to this house. It is a so called “trombe wall”. I’ve discussed it in our previous article about solar thermal mass windows. But this time, the Boston Solar Home will have new and improved solar thermal windows: these are not the old 2×2′ window blocks. It will be a full size 8×2 wall/window units, covering the entire south side of this solar house to provide it with all the heat it will need in the winter. To avoid overheating in the summer, the roof will overhang the southern side by 3 feet, and an additional retractable awning will roll out to provide the shade for these thermals walls / windows.

The walls of this solar house have 2 inches of ISO insulation on the outside and 6 inches of between studs insulation. In total, there will be more than 30-r in the walls. Although this is a stick construction home, it can easily be labeled as super-insulated, and it will have minimal heat loss, while providing more than enough energy to be completely off the grid, and won’t need any outside energy sources for either heating or cooling.

Portable design of this Solar Home:

For the purpose of the competition, the house has to be transportable, therefore it is designed and built in 3 sections on portable foundation blocks, so that it can be put on flat-bed trucks and transported to DC for the competition, and then transported back.

The house is designed to be easily taken apart and put back together: All the mechanical components, bathroom, kitchen, heating and air-conditioning equipment and electrical panels ate located in one part, and special quick connect ports are used when two living sections are connected. Solar PV panels and solar thermal system are installed on removable racking systems that are mounted to the parapet walls on the roof, eliminating any roof penetrations and potential roof leaks. This also allows for easy removal and re-installation of both types of solar systems.

There will be a fold-able / removable deck / patio area with a handicapped access ramp, making this home a perfect choice for comfortable living in the summer and winter, and usable by anyone.

Final thoughts about the solar house:

Since this solar home is still in the construction stage and many systems are not installed yet, it is difficult to get a complete picture of how it will perform. Still, this will be a true zero-energy home, and will actually produce a lot of excess electric power to be sent back into the grid. My biggest personal concern about this home is the cost: without having the exact information and costs run down, the estimates are around $800,000. This amounts to about $1000 per square foot of living space (a maximum of 800 sq. ft. of living space is one of the guidelines of the Solar Decathlon competition), which is very expensive and is not very practical. However this is just  a prototype and if it was a mass production home, the actual cost would be a lot less. This cost also includes the transportation to and from the competition site in Washington DC, and nominal expenses such as marketing, promotion, creation of the website, etc. So the actual construction costs are somewhere around $500,000-600,000.

This is just the firs report on this solar home, and there will be more, as construction goes on. Stay tuned for a complete report on the roof and solar PV system installation, as well as overview of the new solar thermal window units.

Useful resources:

http://www.coolflatroof.com/flat-roofing-blog – Learn about the green cool PVC roofing systems, solar roof products and metal roof installation methods.

http://www.mbmcarpentry.com – Green construction and home improvement in South-Eastern Massachusetts and Rhode Island.

MA Metal Roofing – Flat roofs will not always fit the design of a solar home, and that is where the greenest roofing technology – a Metal Roof – is a perfect fit for any sloped roof design.

]]> http://www.greensolarcafe.com/green-construction/boston-solar-decathlon-home-with-ib-flat-roof/feed/ 1 http://www.greensolarcafe.com/renewable-energy/solar-metal-roofing/ http://www.greensolarcafe.com/renewable-energy/solar-metal-roofing/#comments Thu, 04 Sep 2008 23:16:05 +0000 roofingwiz http://greensolarcafe.com/?p=16 The most economical Solar Roofing combination is to use a Standing Seam Metal Roof with Thin Film Solar Panels – a practical and sustainable option for residential Solar PV installations.

In this solar roofing guide you will learn about pros and cons of metal roofing with laminated thin-film solar PV panels manufactured by Uni-Solar Ovonic, or simply UniSolar which is an Energy Conversion Devices company/brand.

UniSolar thin-film solar panels have been specifically designed to be installed with a standing seam metal roof and have a nominal width of 15.5 inches, which fits perfectly into a 16″ standing seam metal roof panel. With a special butyl adhesive backing, the installation of thin-film solar panels is very simple and fast.

Watch how the the solar metal roof is installed and how solar panels start producing free electricity right away:

Solar Metal Roof Installation video:

Benefits of Solar Metal Roofing and roof-integrated solar systems:

Solar metal roofing is the most cost effective way to get a lifetime roof installed together with a solar PV system. The saving comes from the fact that the installation of the solar system is greatly simplified, because there is no need to install the racking system, which holds conventional solar panels. This saves you about $1 (one dollar) per watt DC of solar system, and eliminates an additional $.50 per watt for the installation of the racing system and solar panels. With thin-film solar PV laminates, the installation is reduced to cleaning the inside of the metal roof panel, applying and rolling in the solar PV laminate and installing the metal roofing panels.

Later, when all the standing seam metal roofing panels have been installed, the solar integrator connects the mom and pop contacts on each solar panel to form one, two or more strings of solar panels, and runs the wiring down to the inverter, which then converts the DC power from solar panels into AC power at 240 volts and feeds the electricity into your home’s power network. All excess electricity is sent into the grid (for grid-tied solar systems), or to your storage batteries (for off-grid solar systems). You can use solar calculator to estimate the cost of solar system and calculate solar roof price

Why use roof-integrated solar system vs. conventional solar panels?

The main problem associated with general Solar PV systems that you can now see on many homes around the country, is the fact that an asphalt shingles roof will fail much sooner than the Solar panels. When that happens, those home owners will be faced not only with the re-roofing expense, but also with complete removal of the solar array and re-installation. This MUST be performed by both the roofer and the solar integrator, as the roofer alone will 99% of the time screw things up. And bear in mind that a roofing warranty will usually not cover damages to the solar equipment, let alone all the possible short-circuit type situations.

The additional cost associated with these procedures should be at-least the same as the cost of the new roof itself. Think about it: Electricians unlike roofers have to be licensed. An apprentice electrician needs at-least 4 years of schooling/work experience. This is like an undergraduate degree. A master electrician needs another 4 years. Therefore, electricians usually charge $75-100 per man-hour. You’ll need at least two electricians for this job, which will take a whole day to remove the panels and another day to put them back, if not more.

The math is simple: 2 guys * $75/h * 8 hrs. * 2 days = $2400 plus any possible parts and supplies that may be required. So let’s say it costs you $2500 extra. In some parts of the country that is how much an average 1200 sq. ft. cape house roof will cost today with the material.

Metal Roofs vs. Asphalt shingles

Unlike very “popular” asphalt shingles, metal roofs are pretty much permanent. They are for the most part, produced from recycled metals, and when installed by a trained professional, they will not leak for decades. Read more about residential and commercial metal roofing .

Metal roofs combined with Renewable Energy technologies can create a perfect combination of light, long-lasting and affordable solution for Solar Electric and Solar Hot Water, as demonstrated in the image to the below:

There are other numerous benefits to having a metal roof combined with Solar PV and other renewable energy technologies. When looking at a metal roof vs. asphalt shingles, also consider that a metal roof will save our land fills from getting more shingles dumped there in 10 years or so. Combined with beautiful looks, you get a permanent roofing solution, various solar technologies, and when paired up with a geo-thermal system, you can easily design a 100% energy-free home, with great curb-appeal.

Check back in a couple of weeks for a complete Solar Metal Roofing Guide.