Back to the Future: A Smart Energy District

This is a guest post by Raymond Kaiser, LEED AP, Director of Green Building Services for Stewart Engineering Consultants. Mr. Kaiser has considerable experience in renewable and sustainable energy strategies and technologies. He has provided energy and environmental consulting to State and local agencies, private developers and engineering firms for over 10 years.

The Historic Green Village at Anna Maria


Today’s power industry is built around centralized generation, transmission and distribution of electricity utilizing primarily coal, natural gas and uranium as fuel sources. For several years, a new model for more distributed generation and delivery of energy services has been evolving, and a product of this evolution is the Smart Energy District. A Smart Energy District includes a range of alternative energy sources, energy efficiency measures, intelligent energy management of distributed resources and loads, and internet-based monitoring that provides real-time feedback on energy consumption. Implementing a new energy architecture across several buildings (i.e. a district) can reduce capital and operating costs, increase energy efficiency, and accelerate the transition to a renewable energy economy.

Surprisingly, the setting for this new distributed energy model is Anna Maria Island, a barrier island on the Gulf of Mexico that has retained the look and feel of Old Florida. It is a pedestrian and bicycle friendly community, with miles of sugar white sand and a relaxed, easygoing atmosphere.

Several years ago, a vacationing British couple, Lizzie and Mike Thrasher, were captivated by the natural beauty and slow pace of the island and decided to put down roots in the sandy soil. Amidst significant development pressures, they saw the opportunity to simultaneously preserve the historic charm of Anna Maria Island while demonstrating the feasibility of setting a new benchmark for environmental sustainability. They bought five lots on Pine Avenue, the modest commercial center of the City of Anna Maria, on which two neglected historic buildings sat. The Thrashers then purchased two other historic buildings designated for demolition and moved them to the site as well. The result: the Anna Maria Island Historic Green Village.

The Village preserves the historic charm and scale of Old Florida while providing a portfolio of technologies that demonstrate the state-of-the-art in sustainable design and development. The Village generates more energy than it consumes, harvests rainwater and storm-water, and encourages a range of sustainable transportation choices. There is a free public charger for electric cars and golf carts. The City also offers free trolley service – 7 days a week, 16 hours a day-- that arrives every 20 minutes. Beach Bums, the store next door to the Village, rents bicycles, electric golf carts and Go Pets, a Segway-type personal transporter. All of the buildings are designed to meet LEED Platinum level - the highest level of certification from the US Green Building Council (USGBC). From the beginning, the owners have been committed to creating the first Net Zero Energy campus in the US, and with the opening of the Rosedale Café and Sears Cottage they have succeeded. The Smart Energy District was the means to achieve this objective.

Figure 1: Artist's Rendering of Historic Green Village site

The Smart Energy District

The Smart Energy District is not a single technology, but three distinct and still evolving design elements: Solar Technology, A Cool District and a Smart Network.

Solar Technology

The Historic Green Village has Solar PV panels on each building and on (planned) solar car ports, with a single point of common coupling to the utility. This micro-grid allows extra electricity being generated at one building to flow to its neighbor. When more electricity is generated across the entire site than is being consumed by the campus, the extra electricity is exported to the utility to supply adjacent properties on the Island. In addition to solar PV, the Café and (planned) residences have solar thermal panels that generate hot water. Currently, there are 233 solar PV panels with an installed nameplate capacity of 48 kilowatts to power the campus. We anticipate doubling the existing capacity to achieve Net Zero Energy as the next phase of the project is completed. During the first full month of operation (Phase 1), the PV system generated 6,972 kWh of electricity.

Figure 2: PV Production – 30 days

Technical Details



# of panels

PV Array kW

Estimated Annual PV Production kWh

Sears Cottage

Suntech 190 watt panels




Rosedale Café

Suntech 190 watt panels





SolarWorld 230 watt panels




Sub Total Phase 1










Phase 2





Thelma's By the Sea

Suntech 190 watt panels




Bldg F

Suntech 190 watt panels




Pillsbury House

Suntech 190 watt panels




Car Port

Suntech 190 watt panels




Sub Total Phase 2





Total Buildout





Note: All of the inverters are SMA Sunny Boy grid tie inverters.

A Cool District

At least half of a buildings’ energy use is to ensure thermal comfort, i.e. for heating and cooling. The Historic Green Village has a geothermal heating and cooling system that takes advantage of the relatively constant temperature of the earth to maintain indoor thermal comfort. Geothermal heat pumps extract heat from the earth during the winter and use the earth as a heat sink when cooling is required. Strictly speaking, the heat does not originate from the earth’s core, rather, the heat pumps harvest heat absorbed at the Earth’s surface from the Sun. Engineers and scientists prefer to use the term “ground source heat pumps” (GSHPs) to avoid confusion with geothermal power which taps into the heat generated by the radioactive decay of the earth’s core.

The EPA has stated that geothermal systems are the most energy-efficient and environmentally safe systems available. District heating and cooling is more economical since the costs – the wells, pump and heat exchanger – can be spread across several buildings.

Figure 3: Diagram of Historic Green Village Cool District

Technical Details

Typically the ground temperature at 6 meters (20 feet) is equal to the mean annual average temperature at that latitude at the surface. At Anna Maria’s 27° latitude the average year round temperature is 74° F. Given the anticipated mix of uses – retail, restaurant, office and residential – the thermal load for the HVAC system was sized for 250 square foot (sf) per ton. The Cool District at the HGV employs a vertical open loop between an extraction and injection well spaced far enough apart to allow thermal recharge (i.e. the rejected heat or cold dissipates in the aquifer without affecting the water temperature at the extraction well). There is a horizontal closed loop that provides the supply and return water from each building’s GSHPs. The full buildout for the project is 10,000 sf or 40 tons of capacity. At 3 gallons per minute (gpm) per ton the wells need to supply 120 gpm. This required 400’ wells. At that depth the water temperature was 80° F. We have added thermometers, flow meters and data loggers to measure the actual energy performance i.e. the Coefficient of Performance (COP) and the Energy Efficiency Ratio (EER). The well pump is a 5 hp variable frequency drive and the GSHPs are Bosch AP Series Water2Air Extreme Efficiency 4 ton, two-stage units (Rosedale has two). For more details on the geothermal cooling system please contact Tom Stockebrand at stocky(at)alumni (dot)Caltech(dot)edu.

A Smart Network

Each building has an e-Monitor from Powerhouse Dynamics that monitors and transmits real-time building energy use for lighting, heating and cooling, refrigeration, and various other “plug” loads, as well as the amount of renewable energy generated on-site. This data has been an invaluable tool in targeting how to effectively reduce energy demand. It highlights when equipment is unnecessarily left on after hours, or when a thermostat is improperly programmed.

Technical Details

To accumulate circuit level data there are currently four e-Monitors. One for each building, one measuring campus loads (the well and irrigation pumps, electric charging stations and landscape lighting) and one measuring all of the PV arrays. The data is remotely monitored by the equipment supplier Powerhouse Dynamics. We are working with the Center for Advanced Power Systems (CAPS) to simulate the performance of the micro-grid and to develop an open systems application framework for dynamically managing diverse generating assets and loads. CAPS is a multi-disciplinary research center at Florida State University in Tallahassee Florida. With support from the U.S. Navy, Office of Naval Research (ONR) and the U.S. Department of Energy, CAPS has established a unique test and demonstration facility with one of the largest real-time digital power systems simulators along with 5 MW AC and DC test beds for hardware in the loop simulation. The center is supported by a research team comprised of dedicated and highly skilled researchers, scientists, faculty, engineers, and students, recruited from across the globe, with strong representation from both the academic/research community and industry. The March 2011 issue of the American Society of Naval Engineers Journal recognized CAPS as "The Only Facility of its Kind in the World." For more detailed inquiries of the modeling of the micro-grid please contact Rick Meeker at meeker(at)caps(dot)fsu(dot)edu.

Energy Efficient Buildings

The most cost-effective means to creating a Net Zero Energy campus is to ensure that the buildings and equipment meet the highest energy efficiency standards. In a typical office, heating, cooling, and lighting comprise about 90% of the energy usage. In Florida’s hot, humid climate, an energy-saving strategy seeks to maximize natural daylight while minimizing excessive solar heat gain. The existing street and building layouts follow the natural topography of the Island, so aside from generous landscaping to provide shade, we had little opportunity to incorporate passive solar design elements and orientation into the project.

Figure 4: Historic Green Village Net Zero Energy Campus

High Performance Envelope

Our initial design focus for energy savings was to create a well-insulated building envelope: the roof, walls and windows, which rejects heat and lets in natural light. Each building has an EPA Cool Roof: a roof that reflects sunlight and emits heat. The insulation for the roof and walls exceed State code (R-30 vs. R-19 for the roof; and R-19 vs. R13 for the walls). More than half the energy (heat) in sunlight is in the infrared portion of the solar spectrum. Spectrally selective windows, specifically developed for hot climates, reflect the invisible infrared radiation. The result is a major reduction of the solar heat gain through the window without significant loss of visible light transmitted through the glass. Cooling represents 40% of commercial energy use in Florida. As previously mentioned, the heating and cooling is provided by geothermal water source heat pumps. Such systems are generally 30-50% more efficient than conventional HVAC equipment. As previously mentioned, we will be measuring the actual COP and the EER over time.


Lighting generally accounts for 20% of energy use in commercial buildings. In retail establishments it’s often almost twice as high, since lighting allows merchandise to stand out. All of the lighting fixtures at the Historic Green Village use LED lamps. These lamps use 80% less energy than the typical MR16 halogen lamp that is typically used in a retail environment. In the Café, lighting accounts for less than 4% of electricity consumed.

Other Plug Loads

Electrical devices such as TVs, computers, printers, copiers and refrigerators not only use energy but also generate heat, thus increasing cooling costs. These "plug" loads represent about 6% of the electrical use in a typical office setting. The Café has a much higher density of electrical devices energy, including espresso and coffee machines, as well as a freezer, display refrigerator and ice maker. The eMonitor has provided insight into the demand profile of these devices. We learned that the espresso machine would heat up at 3 a.m. in the morning, so we added an automatic shut-off timer. The display refrigerator was the second largest energy consumer to the HVAC equipment, so we ordered a thermal blanket to keep in the cold (and reduce the heat generated) on off-hours. This reduced the refrigerator’s electricity demand by 15 to 20%.

During the first full month of operation, the total load (electric demand) was 7,812 kWh. FPL delivered 3780 kWh and the Village exported 2,940 kWh. So in June we are 840 kWh short for our first full month of operations. On an on-going basis we will make operational adjustments (e.g. changing set points) and add additional PV capacity as needed to attain our objective of Net Zero Energy.

Figure 5: Rosedale Café – 30 days demand by circuit

Figure 6: Rosedale Café – Minute by minute demand by circuit

Integrated Water Management

Florida is blessed with an abundance of rain – over 54” per year. But Florida’s population growth combined with the seasonality (rainy and dry seasons) and periodicity (wet and dry years) means that we are most often pumping out groundwater faster than our aquifers can be replenished. The Historic Green Village has an integrated water management approach based on demand management i.e. use less water; and developing alternative non-potable supplies, rainwater, storm-water and greywater.

Figure 7: Historic Green Village Integrated Water Management system

WaterSense Appliances

All water fixtures-- toilets, urinals, showerheads and faucets-- are EPA WaterSense-compliant, meaning they use at least 20% less water than a standard fixture. The urinals do not require any water. Total overall water demand is 35% less than standard fixtures.

Florida-friendly Landscaping

The lush native maritime landscaping at the Village is naturally adapted to the sandy soils, and will produce a root system capable of reaching the ground water table year-round. A representative sample of the native trees, shrubs, wildflowers and ground cover selected and installed include Railroad Vine, Muhly Grass, Knotgrass, Sea Purslane and Coontie. Once established, these native plants will not require irrigation.

Alternative Water Supplies

There are three separate and interconnected alternative water supplies at the Village: Rainwater Harvesting, Storm-water Harvesting and Greywater Recycling.

Historically, barrier island residents relied on rainwater and cisterns to supply their potable water needs. Rainwater is one of the purest sources of water available. It almost always exceeds the quality of groundwater and surface waters, since it does not contain dissolved salts, minerals and other groundwater contaminants. The Rainwater Harvesting system collects water from roof gutters and funnels the water to underground bladders. It is used to supply the toilets. Excess water is directed to the storm-water cisterns. The Stormwater Harvesting system collects water from site runoff and is stored in underground plastic tubes. The system provides water storage for the local fire department (a dry hydrant) and is used for irrigation. The Greywater System pipes water from the showers and sinks to the underground cisterns once it is filtered and chlorinated. This range of technologies has reduced potable water demand for the campus by over 90%.

Technical Details

The rainwater collected from roof gutters and the condensate from the WSHPs is collected in three bladders (two 7’ x 40’ and one 7’ x 20’) under the patio deck outside the café. The total storage volume is 5,225 gallons (7.48 gallons per cubic foot). Overflow from the bladders is routed via a 6” pipe to the stormwater harvesting storage tanks. The stormwater tanks are three 24” 80’ cistern storage tanks that collect site run-off from 18” drain basins. The Greywater Harvesting system is a Brac RGW-350 that treats sink and shower water and then is routed to the cisterns. For more detailed inquiries of the system please contact Skip VerMilyea at skip(at)stormwaterreuse(dot)com.


The renovation costs for the Sears Cottage was $211,000, or $193 per square foot; and for the Café, excluding furniture and fixtures, the cost was $285,000, or $158 per square foot. The Energy District budget is separate because the costs will be allocated to all five buildings on the HGV campus.The geothermal system (wells, pumps, and piping) costs $153,000. The power distribution and PV panels cost $250,000. The PV panels were $6 per watt installed (an existing 25 kw PV array was tied into the Village). Is it all worth it? Traditional return-on-investment metrics suggest not. Yet we undervalue so much – natural beauty, historic charm, walkable streets, the costs of mountaintop removal, altering the chemical composition of the atmosphere, and finally, the rich abundance and diversity of life itself.

As John F Kennedy, echoing an old proverb, said: We are not here to curse the darkness, but to light… (a) candle that can guide us through that darkness to a safe and sane future.”

Truly impressive design and I really enjoyed reading this. It could inspire people to innovate along these lines and if so it will be well worth it. However in my opinion, for the average person/business, the "cost/benefit" ratio will have to be MUCH lower for any kind of broad-based acceptance of the technology. From a quick look at the numbers, it looks like about 1 million $ up-front cost for about $7000/year savings in electricity (at 10 cents/kwHr). Assuming that hot water costs about the same as electricity, the payback time for this investment would be more than ~80 years. It is not just that people are not this patient (they aren't), it is that they just don't have this kind of capital to pay up-front. They are already broke. That problem will get worse in the future. I realize that demonstration of a practical alternative for the average home/business owner was NOT the purpose of this technology and that there are other benefits explained by the author. However, we will need more practical and cost-effective alternatives and demonstrations thereof, if the grid doesn't survive the coming energy shortages.

iwylie – Good points. Upfront capital limitations and long payback periods are two big inhibitors to widespread adoption of this technology. On the front end, most US homebuyers are focused on maximizing amenities and/or house size for a given budget, not energy efficiency. Electrical power is still relatively inexpensive here, so it’s either not a big consideration, or if one’s financial situation is so precarious that it is, then one probably can’t afford this type of installation anyway. And over the long haul, people in the US tend to change houses every few years, and could not recover their investment over the short time they lived in one location.

And over the long haul, people in the US tend to change houses every few years, and could not recover their investment over the short time they lived in one location.

I highly doubt that this particular trend will continue over the long haul and IMHO, there is a fundamental flaw in the concept of regarding houses as financial investments which will provide a profitable return.

As for Electrical power still being relatively inexpensive, get yourself a large soda and a bucket of buttered popcorn, then sit back and enjoy your plush seat, in the front row to the show.

They're still showing previews of upcoming attractions but the main feature will begin momentarily...

Anyways, If any of this is to become a viable alternative to the monopolies of centralized energy production by utility companies, it will have to be a societal and community endeavor and probably can't be done independently by individuals. Americans, and many others, will probably have to relearn what it means to be part of a community where people get together and help raise each others barns and share the responsibility of protecting the commons for the benefit of all.

Not that I'm holding my breath or anything.



Note: One should not bet the farm on the idea that one can forever make a profit by flipping the barn!

Fred, I'd be interested to get your take on the PV system. $6/W, installed, seems not unreasonable, though we would all like to see that cost coming down.

Looking at their numbers on production, estimated 106kW at buildout for 141,000 kWh.yr is a capacity factor of only 15%.

Seems a bit low to me - are these panels in less than ideal location/angles/aspect, or is that normal for southern Florida?

Paul, those are good questions. The answer is probably a bit of all of the above. This place is on the other side of the state from where I am, about a four hour drive away. I might drive over some weekend and check it out in person.

The article says they are using Suntech 190 watt panels, here is a link to the specs for those panels.

They are claiming: "High module conversion efficiency Up to 14.9%" That would of course be under optimum conditions of solar irradiance and temperature, not something that Florida is noted for, given our particular climatic conditions.

All in all, I could probably live with these panels. However it is important to remember that as in all cases of PV solar energy, one must make a mental shift and become much more aware of ones energy use and reduce it as much as possible by conservation and be much more in tune with outdoor conditions that affect energy generation. It requires a paradigm shift away from BAU thinking both in terms of the real long term cost benefit analysis and payback as well as overall performance expectations. It is a different way of life but not necessarily a bad one.



Maybe overcast days are not so good in Florida. In the peak months of the summer there are about 5-6 hours of peak sun per day. So the capacity factor can go up to 25%. But in the winter you can get very low amounts of light which are fewer in hours of daylight and in intensity. I think this can run down as low as 10% capacity depending on location.

The nice thing about the capacity increase in the summer. You generally peak in electric use in the summer at least in the Northern hemisphere.

I would also think that today solar can be installed for less than $5/W.

Solar in the states sets all time record generation on a day in May or June. June is the time of the summer solstice.

"You generally peak in electric use in the summer at least in the Northern hemisphere."

Only if you're incinerating things for heat rather than using electricity. Some areas in the south and in Europe do set all time records for demand on winter mornings.

Some areas in the south ... do set all time records for demand on winter mornings.

Do you have any substantiating data to support this?

T'is true in Florida because there is little natural gas infrastructure for residential so most heating is provided by electric strips or heat pumps.

"Florida Power & Light urged customers to conserve electricity as temperatures dipped lower than they have in more than a decade. FPL produced a record peak of 20,190 MW on Friday morning and expected the demand to be higher Saturday morning. Friday’s record was about 1,000 MW more than the previous record set last August."

Yeah, that was an odd claim.. and even if there ARE substantial peaks on Winter Mornings, I'm sure that Texas today, right now, could be selling Solar KWH at a Premium into their grid, being up in record usage numbers, and sweltering under a big bright sun!

I saw something about Ercot paying 30x normal prices for spot megawatts. Like a $1000 per MWH, versus $30? Any generation source would be economical at such prices, probably. I don't know such pricing extends to small-scale generation, though.

The actual cost of the PV panels was about $5.50 per watt. This does not include the federal investment tax credit of 30% for the installed cost as well as the accelerated depreciation. The first deduction (a rebate until 2012) reduces the cost to $3.85 per watt. The value of the second deduction is dependent on one's tax bracket. It's worth an additional 29% less at a 35% bracket and 12% less at a 15% tax bracket.

On PV performance calculations are quite conservative. We don't have solar insolation values from NREL for Anna Maria Island so we used Tampa values. The azimuth and tilt vary among the arrays but with the Tampa values we are calculating 5.09 to 5.21 kWh/m2/day and used a default .8 derate for losses. Our actual performance (as are all our PV installs) is considerably higher but 1. the insolation values are based on a 40 year history and in Florida the last 5 years has been dry to normal rather than wet years and 2. the panels are expected to degrade over time (though Suntech has a pretty impressive performance warranty).

From a quick look at the numbers, it looks like about 1 million $ up-front cost for about $7000/year savings in electricity (at 10 cents/kwHr). Assuming that hot water costs about the same as electricity, the payback time for this investment would be more than ~80 years.

If you apply the time value of money, it would be much longer than that, even at very low discount rates.

From a quick look at the numbers, it looks like about 1 million $ up-front cost for about $7000/year savings in electricity (at 10 cents/kwHr). Assuming that hot water costs about the same as electricity, the payback time for this investment would be more than ~80 years.

If you apply the time value of money, it would be much longer than that, even at very low discount rates.

Whot if the price of electricity is $70,000/pr year? Following the oil price up, I mean?

Tor - Good question. As stated in my original post, low electric power prices are a big part of the reason for long payback timeframes. If the price of electric power were to increase dramatically over the near term and everything else stayed the same, then payback timeframes would decrease. But if the price of electric power were to actually increase 400% [i.e., ($70K-$14K)/$14K] over the near term, then it’s very likely everything else would NOT stay the same, and it’s anybody’s guess how the rest of the equation would change. Maybe such an increase would coincide with a period of severe overall price inflation. In that case the discount rate you’d need to use for payback evaluation would also need to be significantly higher, offsetting some of the payback improvement. Maybe under such a scenario, the average homeowner’s purchasing power would have been degraded to the point where this type of installation would simply not be an option, no matter what the improvement in payback period. It’s really impossible to predict. IMO, the best you can do is to make your most reasonable assessment of the future and spend your money accordingly.

The #1 thing that could change the equation is a significant reduction in the upfront cost of these systems, either through manufacturing breakthroughs and/or tax incentives. If the people who build these systems figure out how to do it much more cheaply, or if the government allows me to use other people’s money to install one on my house, then I’d go for it in a heartbeat. In the meantime, I’ll keep paying my trivial expense for electric power, let the power utility have all the fun and responsibility for maintaining the system, and direct my funding and mental energy toward other endeavors that I expect will give me a better payback. No offense intended to all the fine folks whose own crystal balls show a different future.

The #1 thing that could change the equation is a significant reduction in the upfront cost of these systems, either through manufacturing breakthroughs

Agreed absolutely, though I think the breakthroughs are more likely in installation and balance of system costs

or tax incentives

Disagree - mostly . While tax incentives/subsidies are nice, they are not scalable. As soon as enough people start doing it to make a real difference, the government is running out of money that is needed for real services (water, roads, schools, etc), or else is going into debt - is that really a good way to go?

The are only two "tax incentives" that I think are scalable are;

1) a carbon tax, but that is not something any US Federal or State government seems likely to enact.
2) allow a 100% depreciation of investment in any renewable energy system

One other possibility is for the feds to loan money at 0% interest for these projects - instead of loaning it at 0% to the Wall St banks. At least this way something useful gets done!

Paul - I agree that tax incentives allowing homeowners to get systems for "free" are not scalable, and I wasn't advocating it as a long term national strategy. I was just observing that if such an incentive existed at a given point in time, an individual homeowner would benefit from taking advantage of it.

Impressive and cool but I don't get the title. "Back" to the future? If anything it is the centralized-generation-only model that is old fashioned and distributed generation that is new, and using newer technology like modern PV.

Back to the Future refers to the historical nature of the commercial district (historical buildings/old Florida/walkable streets) and also hints at the fact that the first energy districts were located in close proximity to their customers and provided both heat(steam) and power. Over time the scale of the plants and the associated emissions pushed power plants further and further from the demand loads.

oddly enough, the back to the future also applies to the electricity utilities. In the early days, they were all community based systems - there was no grid interconnecting cities. Hence the plethora of utilities that were called something like the "Smallville Power and Light Co.
As the grid was developed, and large steam turbine based coal plants replaced smaller steam engined plants, centralised generation and grid distribution simply outcompeted the local power co's and gradually bought them out.

We are now seeing a bit of a reversal, with a few cities/towns taking back their electric systems, with a view to encouraging more local generation.

"We are now seeing a bit of a reversal"

What happened to the idea that areas with great wind resources would send power to far away areas that don't have wind resources? Also, what happened to the idea that areas with great insolation would send power to areas that don't have great insolation?

Has the Desertec idea been scrapped? Is Germany *not* going to ship excess wind generation to other countries?

What I see is more resources being used to generate a given amount of power. More consumption of materiel.

Both can be true in the same universe, SA.

More people are looking to home and community power solutions, but even the SAME people (ie, ME) are willing to consider a diversified portfolio and let another option be the creation of larger renewable energy sites in Deserts, or in the Bay of Maine, near me, and Power Corridors for them, which could make a very helpful complement to a more distributed plan.

Nice to see what solar looks like at the community.

Unfortunately, Most of this community may be under water before the century is over:,1518,774706,00.html

"NASA climate researcher James Hansen, for example, warns in a paper published this month that sea levels could rise by five meters in the next 90 years -- nine times higher than the maximum cited in the last IPCC report. He insists that he has found indications that sea levels in the future could rise by as much as five centimeters per year."

To see what a five meter sea level rise does to the island, see:

(The island is just south of St. Petersberg on the west coast of Florida.)

How much energy will be involved in moving the whole thing to the mainland (much of which, of course, will also be under threat of rising sea levels, especially in Florida.).

Having lived in New Orleans in my school years, I would never build anything on land below 30 feet above sea level. The courthouse in either Biloxi or Gulfport, MS was at 30 feet, had one foot of water covering the floor during Katrina. Also, I wouldn't use any building material other than reinforced concrete in a hurricane area (My house is concrete). The cost for concrete is an extra $10 per sq ft. I went for the more expensive aerated autoclaved concrete, which isn't as strong as poured but has high insulation value. Concrete is also termite proof, which is very important with the spread of Formosan termites. The other thing most builders and miss is the orientation of windows to the sun. Tall windows need to face south or be under an overhang, but overhangs should be avoided in hurricane areas.

Wind insurance along the coast now costs a fortune. Most insurance companies pulled out of the coastal market leaving the state pool as the only insurer in many areas. Having a wind resistant house I don't carry wind insurance, which would cost twice what my electricity cost. Anyone with a mortgage is required to have the insurance.

Off the Louisiana coast was a posh resort in the antebellum period on a place called Isle Dernieres or Last Island that was destroyed in the 1856 hurricane. Many of the wealthy planters families were lost. The book is fascinating.

Last Days of Last Island: The Hurricane of 1856, Louisiana's First Great Storm,_Louisiana

I'm surprised that your modest list; 30' above sea level and reinforced concrete are not required for reconstruction. Perhaps 50% of the house being reinforced concrete as a minimum, a kitchen, bathroom, bedroom.

Oregon has new seismic rules for construction. The foundations look like bunkers and the top floors are bolted all the way to the foundation.

Sounds a lot like the three little pigs...

The tornadoes in Alabama did a few billion dollars damage this year, plus costing over 300 lives. Had we not had warnings like in the days before radio and television, the Tuscaloosa tornado might have killed thousands.

Due to the increases in insurance rates, a proper re-rating system for fortified houses should save enough on premiums to offset the higher expense of construction. The Institute for Business and Home Safety has a certification program that may result in lower premiums, in most cases not more than 25%. You must have plans approved in advance and on-site inspections during construction.

Any extra expense in PV, or other energy generation or conservation systems only increases insurance premiums.

The gulf states always seemed 'more poor' to me than other parts of the nation. Having several billions of wealth be it buildings or crops destroyed semi-regularly would depress any economy, anywhere. I like the fortified house as a good starting point toward minimizing longer term economic problems.

Batteries is my question. I cfould not find a mention of batteries in the text. All the PV systems and most of the home power renewable systems I have seen use a room full of batteries. Batteries for home power usually means dozens of lead-acid batteries which are expencive to buy, have a limited working life (3-10 years), they are toxic, easy to damage, and need alot of energy to make.

The critical technology which would make small, local power more viable would be a cheap way of storing electricity.

Mechanical pumps have similar issues of high cost, short life and high embodied energy. They are as costly and complex as piston engines so not a proper renewable technology. Ground source heat would need to work without the usual piston pumps to be renewable, eg by convection.

I think the future will be sailboats, wood fires and horses.

There is no need for batteries - that is what the grid connection is for.
Connecting to the grid, and using that to "store" your surplus is far, far cheaper than having battery banks.

Storage is not what is needed to make local power more viable - it is lower capital costs.

Then connect to grid and let some centralised NG turbines take car of the peak loads, and a few coal/nuke/hydro plants to take car of the baseloads

If community can generate even half of its total power, that is a major step forward from today, where typically they generate zero. Trying to get to 100%, and separate grid (meaning storage) will increase costs by 10x for 2x more power - how many communities can afford that?

As we move into a situation of regular brown-outs, what's going to be needed is a temporary battery bank (eg less batteries, but enough for x hours) and an isolating grid-tie such that you can maintain resilient supply.

Most grid-tie systems being installed seem useless in this respect, since they shut down the power if the grid fails.

Interesting, maybe I'll visit this place some weekend and see if I can learn some more about it.

A very impressive project; congratulations.

It would be interesting to learn how well this GSHP performs vis-à-vis a VRF air-source heat pump. For example, the Sanyo CHDZ07263 which can simultaneously heat and cool has a nominal cooling capacity of 72,000 BTU/hr. In cooling mode and at an outdoor ambient air temperature of 35°C/95°F, the compressor draws 5.3 kW which gives us a COP of 3.98. This particular unit has a nominal heating capacity of 81,000 BTU/hr and draws 5.79 kW in heat mode which translates to be a COP of 4.1. (Source:

Taking into consideration the amount of energy that would be required to lift as many as one hundred and twenty gallons of water per minute four hundred feet, I can't see much if any advantage, particularly when the temperature of this water at 80°F in not significantly cooler than the average air temperature.


A GSHP closed loop would seem to use a lot less power, as there is no net lift, just frictional losses.

A good air-cooled HP for sensible cooling along with a dessicant dehumidifier for latent cooling would seem like good combination for such a locale. 80F would be a nice temp for the absorber loop, prior to a sensible cooling stage. Higher air flow would improve the HVAC COP if it didn't need to lower temps far enough to de-water.

There is advancement underway for dessicant cooling and for high-efficiency air heat exchangers. Both should move AC closer to theoretical limits.

You might be able to do something clever with heat recovery and use the AC to heat the hot water. You could also use ice storage to shift some of the demand to off peak.

Also PV and micro inverters are getting cheaper, so you could probably build a similar system today with todays PV prices and ASHP over GSHP at a much lower price

A café would presumably have a high demand for hot water which makes a heat pump water heater a good choice. Two to three times more energy efficient than a conventional electric water heater and free cooling and dehumidification; in effect, two services for the price of one.


Mr. Kaiser,

It seems the high cost items in the design are the Geothermal cooling and the PV needed to power that system. Have you explored using liquid dessicant for dehumidification to lower the energy requirements in cooling?

Very cool and elegant looking passive technology. And for our climate zone latent load is the challenge. We have a fair amount of experience with a passive dehumidification technology based on a membrane initially developed for fuel cells - see

That scheme is clever (though the web designer, who forced too-small text into forms which the user can't scroll easily once expanded, needs a LARTing).

The one thing I'd be concerned about WRT calcium chloride is the propensity for chloride salts to cause corrosion; any leaks or aerosol droplets could create enormous damage in nearby electric gear, electronics, artwork, structures with steel fasteners.... I'd feel safer with the absorber behind a HEPA filter.

You voiced my exact concern. I can only imagine it dissolving my electrical box or boilers. I wonder if using some kind of air vortex shape to the air flow channel after it passes the waterfall would throw any droplets again the wall. Kind of like a Dyson vacuum.

Lithium bromide is also used as a dessicant, but I've been unable to find prices on bulk quantities (and not chemical/reagent grade) of the stuff from US suppliers.

I like experiments of a comprehensive nature, like this one. The best point from these discussions has been not to try to gain too much, take what is efficient to take for gains, but the extremes are costly. However lots of small scale systems integrated and well designed can pay for us all, so the extreme costs may be dismissed as experimental investments. When we get centralized systems to deliver and store our sustainable energy, and utilities improvements along with that, then we can plug into these systems to use the energy. These systems can't be scaled if they're not piloted. I think the forms will be compressed air, hydrogen and others. We need small scale models of this, off grid with storage. Having said that ideally our new systems must overlap and interface with the old. Overall if we don't pilot, we're bound to fail, and failure to keep an open mind is why future systems will not be piloted.

There are two things that can make this approach more economically viable - 1. select a state that has robust renewable energy incentives (NJ, CA, NC, et al) and 2. do a project at the next scale - 50,000-100,000 square feet with thermal load diversity. A bonus would be to select a state with higher electricity prices (>15cents per kWh). Given these conditions, a tenant that used 1/2 as much energy would pay the same amount for electricity but their implied rate would be higher i.e. they would be using 10 kWh per sf annually rather than a more typical 18 to 20 kWh but their "adjusted" rate of electricity would be 22 cents per kWh vs 12 to 14 cents per kWh.

You must remember that Anna Maria Island is basically the super rich of Sarasota. I've worked Master Antenna TV systems there. The air-conditioning must be very cold, and the lights very bright.

This is how rich people do ecology. We call it demonstrative greenwashing. A far superior system is a solar panel driven ammonia central cooling system using a synthetic oil heat transfer. We built one on Big Pine Key back in the Eighties: heat, cold, electricity, freezer, water pump. Totally off grid. Be even easier now with better batteries and LEDs.

And yes, it's a barrier island. Goodbye.

In Sears Cottage the energy use is less than 5 kWh per sf. NREL's target for net zero energy is 10 kWh per sf nationally. And NREL recognizes that in a hot, humid climate that this is a difficult target to reach. In the cafe with doors opening and closing and people coming and going the AC will be running. But the set point is at 74 degrees F and is switched to 80 degrees F off hours.

The lights are very bright - they're LEDs and they consume very little electricity.

We've looked at solar driven absorption chillers. We designed one for a site in Tulsa driven by 2,000 solar thermal panels.In this project they were a pony chiller meant for peak load. Without gas backup and/or a cheap way to store medium temperature heat they're not very practical.

Where in Tulsa?

How cheap is cheap enough, for temperature storage? Might it be possible to store "latent dehumidification" in a calcium salt tank rather than heat or coolth?

Calcium chloride is cheap enough to do that, certainly.  You'd just have to allow for the expansion of the stored liquid as it accumulated water.

The Tulsa project was never built because NG prices collapsed and it became uneconomic.

I've heard of using molten salts for storing medium temperature heat but don't understand your comment regarding calcium salt. Regardless we have to handle latent and sensible load.

An absorption dehumidifier based on calcium chloride or such generates low-humidity solution using solar heat (or secondary heat), and that "dry" solution can then dehumidify building air, with a fairly low-temp reject heat source for resulting exothermal release.

During the day this is no big thing -- you simply cycle the absorbant. At night, with no solar heat source to regenerate, you could store heat. But you could also store "dry" instead, if you have extra absorbant.

Then, at night, you simply circulate the stored dessicant and de-water the indoor air, and reject the heat as before (but presumably to a lower-temp nighttime sink).

Dessicant systems should greatly reduce HVAC consumption by addressing the latent load via dehumidification, so the classical system only needs to cool the dry air sensibly, and can do so with a better COP since the exit temp doesn't need to be cold enough to condense. You can also over-dry the recirculated indoor air , re-cool, and then water-spray to evaporatively cool the indoor air, if you have spare dessicant capacity.

Unfortunately I don't know of any vendors for the full solution, but I've read of such tandem systems built from off-the-shelf systems (standard HVAC and commercial dessicant system) that worked.

I suspect such a system would work well in coastal climates, where presumably humidity creates a bias toward latent loading.

I have mused about having a multi-phase, multi-concentration calcium-chloride system that used the same solute for dessication and thermal storage, but haven't done the math to see if phase changes overlap in useful areas. Having the ability to have a large tank of the same solute able to store dryness in the summer and heat in the winter would seem to have some advantages, though.

Ray (Razrmon) is using old data. We have upped the temperature for cooling from 72, where the A/C folks set it,gradually (one degree higher each week) to 77 with no complaints. As a result, we have saved almost 20% on our A/C bill. In general, people here in FL complain about the business places being much too cold but apparently the businesses are not yet moved by the information.

In general, people here in FL complain about the business places being much too cold but apparently the businesses are not yet moved by the information.

That is not just a Florida phenomenon - it happens everywhere - California, Canada, Australia.... The stores like to be cold so that people feel good as soon as they walk in, but if you are there for a few minutes, wearing light summer clothes, and have any amount of sweat on your skin from being outside, then you get quite cold, quite quickly.

Oddly enough, one place I went to that had it right was the Fairmont Acapulco Princess Hotel in Mexico - they had their A/C at enough to take the heat off, but not enough to be too cold.

I have seen *many* convenience/general stores labouring under excessive A/C load, trying to keep the store space cool, even as all the beverage fridges dump their heat into the store space! At some point, those "free" fridges from the beverage company start to cost real money - then it is time for a proper coolroom type fridge and central refrig plant, with an external heat dump - makes a big difference to the power bill. I have seen one store, and one only, that used said heat dump as a preheat for the hot water - for both the store and the adjoining car wash!

There are many efficiencies to be had, but typical "retail planning" is all about presentation, not energy efficiency. That's why Paul from Halifax is doing such a good business..

And the converse is true in the winter. I am nearly positive that some stores are colder in the summer than they are in winter.

Yes, that is exactly true, for the same reason.

At the Ski resort where I used to work, the retail manager played this game to a T. He had the main store (skis, apparel, "logowear" )warm enough in winter that people would come in, and feel warm enough to want to stay there, and then take off their ski jackets because it was so warm. Once they are walking around without their jacket, it is easy to try on a "logo" fleece or the like. After being told this I observed people in that store and sure enough...

In summer he still managed to shift a lot of those high margin logo fleeces, because the store was cold, and people, wearing their t-shirts would feel these fleeces and want to try them on. Then when they went back outside, the temp difference was such that some would just turn around and come back in!

sheeple indeed!

Yep, that's why fridges need connections like clothes driers to take the hot air out through the wall. If it's cold outside then, by all means, recirculate to warm the room.


I installed solar PV back in 2008. Did it myself for about $4.50/W installed with Unirac mounting before prices plummeted by about 50%. I sized it to provide all electric for the house and for an electric car. I converted a car to electric in 2009. It has about 75 mile range mixed highway/city, 90 mph top speed. It is very reliable transporation, and the LiFePO4 batteries are still as strong as when new. Cost about $20k. That is about $40k out of pocket in panels and car. Almost everyone who has spoken to me about the panels and/or car asks the same first question and has the same response: How much did it cost? That’s too much. I don’t understand this attitude. I am a very frugal person who lives far below my means (which is why I had the $40k to spend), so why would I spend the $40k that most others won’t? Because I asked myself: How much the planet is worth? How much are the lives of future generations worth? Framed this way, it was a no-brainer. Buy the panels, convert the car. Reduce, Repair, Reuse, Recycle. Reduce your impact. Try to leave a decent world for those humans and all other species that follow you.
So why don’t others of similar financial means come to this conclusion? Because they self-justify and self-delude. Oh that peak oil and climate change stuff is all baloney, no need to do anything. Even if it is real, “we” (we killed a bear, paw did) will figure out a way around them and everything will work out fine. It will all be taken care of by me and others just maximizing our own self-interest. I’m not a bad person. No reason to feel guilty. Heck, I’m a damn good person because I am doing a hell of a job pursuing my own self-interest!

Almost everyone who has spoken to me about the panels and/or car asks the same first question and has the same response: How much did it cost? That’s too much. I don’t understand this attitude.

Neither do I! And a lot of the people who say it costs too much probably spent at least 35K or more on their SUV.

64 thousand dollar question

If the babe comes with the panels then maybe you'd have a persuasive argument Fred.

Sounds like a nice setup.
What is the car? Did you find an EV conversion kit, or pick/match components on your own? (Listed on one of the EV Album sites..?)

With cheap oil, all other values are extremely jumbled, and people have been in a very unrealistic environment, with so few buying choices really built on Essentials and Bare Necessities.


The display refrigerator was the second largest energy consumer to the HVAC equipment, so we ordered a thermal blanket to keep in the cold (and reduce the heat generated) on off-hours. This reduced the refrigerator’s electricity demand by 15 to 20%.


Just a comment here: people can save 80%+ of the power their refrigerators use by using a chest freezer controlled by an external thermostat instead.


  • 1 x chest freezer
  • 1 x digital thermostat (you can buy one from amazon, see below)

Examples: 1, 2, 3, 4.

Buy the thermostat from amazon:

Get a chest freezer (they can be bought cheap on craigslist):

Some consumption numbers would be nice. A large EU A++ rated refrigerator/freezer uses about 200kWh per year.

What is the basis for the savings? Are the freezers better insulated? For a lot of people the extra space needed is a significant obstacle. Where I live the extra 1m^2 of floor space used would cost about $2000, which could buy you a very efficient refrigerator. Also, it seems the freezer would be harder to fill without making the stuff at the bottom inaccessible.

What is the basis for the savings?

There are obviously a lot of factors to consider.

Here's just one: Every time you open the door of a vertical refrigerator the cold air spills out and the compressor has to kick in to cool the warm moist air that replaces it.

In a top loading freezer if you open the top, the cold air just sits there and doesn't spill out...

Also, it seems the freezer would be harder to fill without making the stuff at the bottom inaccessible.

Excuses, excuses, excuses!

I keep looking at the (TWO) chest freezers we use, and wonder how much I could improve with a great sheath of insulation added to them.. only I'm unsure of which surfaces are used to expel heat, and the last thing I want to do is trap that heat inside!

But it occurs to me again and again that the size of our fridges and the thickness of the insulation was made largely as an economical and marketing balance, and that even a bigger box, but with lots more insulation could yield a far better fridge.

The compressor/coolant equipment is really sized for the rate of heat loss more than the 'size of the box'..

Hi Bob,

I'm guessing most if not all chest freezers expel heat on all four sides to help minimize the risk of condensation. The only surface that you could safely insulate is the top.

I plugged the two older (and lightly loaded) chest freezers at my church hall food bank into a power monitor ( I don't remember the exact numbers, but their usage was considerably higher than anticipated. The church replaced both with a single energy efficient deep freezer and their power bill dropped significantly -- something in the order of 150 kWh a month as I recall.

The hall also had two Bunn-O-Matic coffee makers that were used basically once or twice a week ( I discovered that each drew 75-watts just to keep the water hot in their reservoirs. Simply unplugging them when not in use saved an additional 100 kWh per month.


only I'm unsure of which surfaces are used to expel heat

Take a look in the compressor compartment and see if there is a coil there. Just had to replace my fridge and it doesn't have a condenser on the back but I can see a big coil in the base, must get the cover off and take a good look. See if you can feel any heat on a panel, if you can't tell try taping a small slab of thick foam (1-2 sq ft of 1-2 inch) to it, maybe put a thermometer behind the slab. If it gets warmer behind the slab then it is a radiator. If it gets cooler then you are safe. Try various places on each side in case only part is used. The lid should be safe and the base. There may be a heating element by the door seal.

Putting some insulation between the compressor and the compartment may be a good help. One problem may be condensation, I tried some 2" slabs on my old refri but had a LOT more condensation around the door seal area. I am thinking about up rating the new one but that condensation plus termites make me a bit nervous. I did wish I had the foam on last night as we lost power for the night :(


Thanks for the thoughts.. NAOM and Paul.

..sorry about your outage, hope the losses weren't too bad.

I've got an area in the basement that has been developing into a root cellar, but I might just make it into a walk-in, or fridge capable, find a compressor&coils, and just give it a foot or more of insul. with freezer space within..

More busy dealing with coming winter at this point.

FM - And not a very good excuse either. When I had my last chest freezer I salvaged (got free) some racks from an old fridge, cut to fit and layered them in the freezer on short 2X4's with gaps so I could reach down between and pull stuff of the bottom. Not only easy to get the bottom but makes organizing easier. Plenty of room: I had a mid size chest and even when I hunted a lot I didn't miss the space I gave up. So unless someone needs to store several hundreds #'s long term this approach should work fine.

But you are using yours as a freezer! The idea was to convert them to refrigerators, where items are accessed much more frequently.

bio - a freezer. And accessing several times a week. Always kept meat, especially game, frozen until ready to thaw and cook. If I didn't sketch a good mental image: I could reach into the freezer and directly touch every item. Gave up about 20% of the space but still enough enough for 150#+. And as I depleted I used the ole water jug trick to take up the newly emptied volume. And then when I went on a hunt or to pick up meat from the processor I would use the frozen jugs for transport back home. Rather efficient compared how I normally did everything else.

Rockman, we have a chest freezer with chicken/turkey stock and other frozen items. With a little ingenuity we can access everything well enough. I worry about the efficiency from time to time, but our other fridge/freezer in fairly efficient and smallish for freezer storage. The freezer is great to store ice. We even restore ice from our cooler after camping to use it again the next time we go camping or have a party.

Oct - Been thinking about geting a small chest. Got a new fridge with a big bottom freezer. Thought it was big at first, anyway. Not too much game these days but like to stock up on cheap ribeyes and lamb. A small chest runs less than $200 and I've got a closet I can stick it in. And best of all: I'll have room for BLUE BELL! I think I'm ready to fall off the wagon big time.

That is my plan for the new fridge. It is smaller but I will put a freezer in the garage. I will use the freezer for bulk and keep it really cold, maybe added insulation. The freezer in the fridge I will keep a lot less cold as I will only keep stuff in it for a short time so winning back some of the consumption from the freezer. All combined I doubt I will use any more electricity than my old fridge/freezer used, possibly less. A side advantage will be that any ice-cream in the fridge/freezer will not be as rock hard as when in comes out of a deep freeze.


You can still keep a selection at the top and things like beer, soft drinks, packets etc at the bottom. Use square buckets so things can be lifted out easily. If using a freezer and Rockman's trick, try using salted water with enough salt to reduce the freezing point to -10C. If your freezer starts to warm up then the salt ice melting will pause the warming, that saved me big time last night. The salt ice will also keep the meat cooler when you are buying it as well ;)


Some consumption numbers would be nice.

Please follow links to the examples linked in my original post. They contain stats and consumption numbers.

The display refrigerator is for displaying items for purchase - like pastries.

There are top access ones. If you feel you are loosing vertical space put shelved items above. Match the shelf contents to the fridge eg sweet sauces over pastries.


That's quite interesting.

I have seasonal needs for different cooling, I'm guessing that the chest freezer would function as a freezer when the one thermostat is disconnected, and it's internal, regular thermostat allowed to operate? Simple as pulling the plug, or do you have to remove the freezer thermostat to get it operating again as a freezer?

I've been toying with just buying a used refrigerator vs used walk-in cooler, expensive, maybe this would allow kicking the can down the road some more. I lost several hundred pounds of cherries this summer due to insufficient refrigeration.

I read about this retrofit. You can simply remore the external thermostat to get back to normal freezing. The external thermostat is going to switch the unit on and off to keep it at refrigeration temps only.

Right. The example #1 in Mamba's post describes an easy solution with an extension cord. The trouble as I kinda see it, all that refrigeration space may promote more laziness, thinking I've oodles of time now to process.

I was just reading over at Clean Technica site about the use of hay for heating the home.Specifically hay pellets which have a high energy input-to-output ratio of 20:1 that compares to 10:1 for wood,5:1 for biodiesel and an extremely low 1.5:1 for corn ethanol.One pound of hay will produce almost 8,000 BTUs.Anyway the article and the TED video seem to really tout hay towards the top of the list for use in home heating.

What are your opinions guys? I guess you would have to have experience with hay before you could give a fair review huh.Thanks.

As interesting a question as that is, it has nothing to do with this thread about a solar community in a place that doesn't need heat.
Why don't you re-post this in tomorrows DrumBeat - that is the open forum.

"Sounds like a nice setup.
What is the car? Did you find an EV conversion kit, or pick/match components on your own? (Listed on one of the EV Album sites..?)"
No kit, just bought components. About 75 mile range (conservatively) for about half highway half secondary road driving, top speed about 90 mph. About 215 Wh/mile (from the AC wall outlet) which is a bit more than 1/5 the energy of the 32 mpg (1053 Wh/mile) rating the original car had. MPGe 156.

Looks like a good conversion, but was surprised to see the $20k cost! Where did the money go - about half for batteries I'm guessing? I make it you have 20.7kWh of storage, which would take you to 100 miles at 200Wh/mile to 100% DoD.

If you were doing it again, is there anything you could/would do differently, and anything to get the cost down?

The thing I find interesting about the stats on these EV conversions, is just how little power is needed for moderate cruising. 220Wh/mile at 60mph is just 13kW/17hp - about the power of a lawn tractor!

If the Swift was a bit more aerodynamic, and with Prius type low rolling resistance tyres, that number would come down further still.

Thanks for putting all the detail into the EV Album site. I'm often wanting to know more than folks post in there..

I also would like there to be a field for 'Overall, how do you like your car? Satisfied? Convinced?'


Raymond, excellent presentation, I've taken a similar path to yourself on smaller scale (just my own residence).

Islands aside for the moment, areas with large (and growing) populations must pay attention to where the population grows. The LEED for Neighborhood Development adds the all important ingredients of smart location (including brownfield redevelopment) and infrastructure networking (i.e., rail, bus, bike, etc) on top of the green building rating system, which helps to limit sprawl, engender Smart Growth, and reduce Vehicle Miles Traveled (VMT).

USGBC (or more properly GBCI) has been quite inflexible in evaluating this project's access to public transportation. Anna Maria has a trolley that operates 7 day a week/16 hour a day, arrives every 20 minutes and is free. They still didn't allow the access to public transit credit because there are not 2 bus lines even though it's at the north end of a narrow barrier island.

Did you attempt a LEED-ND rating? If so, what score did you achieve? Any other areas that you felt should have received better scores? What changes to LEED-ND would you recommend?

Is the portion below of the rating system that which you take exception with? It appears from the 16 hour/day, ever 20 minutes works out to about 48 trips, which doesn't quite meet the 60 trip requirement - can you confirm?

For the OPTION 3. Transit Corridor or Route with Adequate Transit Service;

Locate the project on a site with existing and/or planned transit service such that at least 50% of dwelling units and
nonresidential building entrances (inclusive of existing buildings) are within a 1/4 mile walk distance of bus and/or
streetcar stops, or within a 1/2 mile walk distance of bus rapid transit stops, light or heavy rail stations, and/or ferry
terminals, and the transit service at those stops in aggregate meets the minimums listed in Table 1 (both weekday
and weekend trip minimums must be met).

Weekend trips must include service on both Saturday and Sunday. Commuter rail must serve more than one
metropolitan statistical area (MSA) and/or the area surrounding the core of an MSA.

Table 1. Minimum daily transit service

Weekday trips Weekend trips
Projects with multiple transit types (bus, streetcar, rail, or ferry) 60 40
Projects with commuter rail or ferry service only 24 6

The first two buildings are in Design Review for LEED NC. Our objective is LEED Platinum. We are also targeting LEED Platinum for the remaining 3 buildings.

If you want to take this offline just email me at raymond(dot)kaiser(at)gmail(dot)com.


Good article.

I was wondering if the author or any of you out there have much familiarity with domestic applications of solar-powered absorption-cycle refrigeration and air conditioning systems.

The distinction here is that an absorption-cycle refrigeration system runs off of heat rather than electricity. As these systems have about the same thermal efficiency of a mechanical compression-cycle refrigeration system, it would appear that one advantage they would have is that a solar heater captures more of the sun's energy than a PV electrical system (something roughly like 50-60% versus 10-15%). Thus, a smaller and cheaper solar energy capture device can be used to supply the same amount of refrigeration. (Or so it would seem to this admittedly non-expert.)

Of course, if you go solar, then such a system would need a means of storing the coldness at night or when the sun isn't shining. This could be accomplished by a installing a loop that would chill a brine solution and store it in an insulated tank in the basement. At night, one would run the cold brine through the heat transfer coils that cool the indoor air. Naturally, the capital cost of such a complete system would be many times that of a conventional electric-powered air conditioner. So I suppose that is an inherent stumbling block.

Yet, it would seem that if such a system is viable anywhere, Florida would be the place.

At one point we worked closely with Solarsa - a Florida based firm seeking to commercialize small (10-30 ton) and large scale solar thermal cooling technologies (200-500 ton systems). The smaller systems were based on Yazaki chillers and for larger systems designs we used traditional gas-fired chillers made by several manufacturers.

They make the most sense as auxiliary devices (pony chillers) and/or where you have natural gas. The economics require fairly high gas prices and also a big spark spread (the delta between electricity and NG prices).