Tuesday, November 21, 2006

Save on Hot Water

source: http://sustainabledesignupdate.com/?p=61

GFX Heat Exchanger

We are working on an energy efficient renovation to an all electric house in Florida. In addition to using renewable energy we are looking at greatly reducing energy use. One of our energy saving strategies is to use a waste water heat exchanger. These devices efficiently pull heat out of waste water and put it into the water heater.

Excerpeted from Rocky Mountain Institute â€Å"Home Energy Briefs #5”

In the average home 80–90% of the energy used to heat water goes down the drain. A water based heat exchanger can capture a lot of the heat in drain-water and put it to use pre-heating the water going in to your hot water supply . One type, called a â€Å"gravity film exchange drain-water heat recovery system” has been found to save 25–30 percent of total water-heating energy. This technology is compatible with all types of water heating systems, but it is especially suitable with on-demand water heaters and solar thermal systems. Prices range from $300–400 and paybacks are in the range of 2.5 to 7 years, depending on how often it is used. For more information on this technology, visit www.gfxtechnology.com.

From the GFX Technology Website:

Perhaps the most important and immediate benefit to owners of all-electric homes is GFX’s power-boost; enough to triple the shower-capacity of tank-type water heaters and halve the cost of a shower. For example, if GFX boosts cold water temperatures by 30 degrees, it’s feeding back about 10 kW of power; more than enough to triple your family’s showering-time and save 2 kW of energy per 12-minute shower. This means if you pay 8.5 cents to 17 cents per kWh for electricity and your yellow water heater sticker shows an efficiency rating (energy factor) of 85%, GFX could save you 20 cents to 40 cents per shower, depending upon where you live and type of showerhead installed.

GFX gives an electric water heater the capacity of a gas heater. In fact, when tested with GFX, the first hour rating of two types of high efficiency 50-gallon electric water heaters tripled to 180 gallons; more than “double the capacity of typical 50-gallon gas heaters” â€" with an energy factor rivaling that of a heat-pump, plus unsurpassed reliability and quietness.

According to U.S. EPA standards, if just 6 million electric water heating systems were to be upgraded by GFX, carbon dioxide emissions would drop by more that 20 million tons per year; the amount released by burning 1.8 billion gallons of oil.

All-copper construction means GFX will last as long as your plumbing system and will pay for itself many times over. Safety is guaranteed by U.L.-approved, double- wall-vented construction and self-cleaning ensures maintenance-free operation at peak efficiency. The falling-film heat exchanger models listed in the table below have ultra-high heat transfer coefficients required for compact size and high capacity.


Monday, November 6, 2006

Solar WiFi

source: http://sustainabledesignupdate.com/?p=57

I have long been an advocate for municipal WiFi systems.

Municipal WiFi systems are municipally sponsored network mesh WiFi internet systems that typically allow low cost and no cost access to broadband connections. As access to information becomes more important for all of us to keep up with developments in politics, culture, and technology it becomes even more important that we don’t leave some people behind.

A municipal government may not come to your mind first when you think about broadband services. Many people may prefer the free market, but municipal governments are in the business of providing roads, police and fire protection, water and sewage treatment. Why not access to information?

Access to information is the backbone of our democracy. Here are a few of the reasons Muni WiFi is a good idea -

Muni WiFi Allows:

1. Municipal and residential scale â€Å"smart metering” of energy use.

2. Traffic congestion monitoring to reduce energy wasting traffic snags.

3. Cost-effective connectivity for both traditional office, mobile and at home workers in Municipal government and business.

4. Untethered access to information which helps improve productivity by allowing City field personnel to work more effectively with office personnel.

5. Complimentary access for visitors and tourists to enjoy during their stays.

Treehugger has an interesting take on St. Louis Park in Minnesota where they propose to go WiFi on renewable energy:

First Solar Wifi City in the US?

St. Louis Park, an unassuming city a few miles west of Minneapolis, may be the first in the country to provide solar-powered wireless internet to its residents. If the idea passes a final City Council vote next week, they will begin the installation of a network of wifi nodes powered by some 400 PV panels situated on public infrastructure around the city. It’s not free however, and through the public/private partnership, residents would be able to pay $15 a month for 128 kilobyte speed or $20 for 1 meg (which does appear to be a pretty decent deal). As reported in the Star Tribune, the city expects to save $40,000 to $50,000 a year by using an entirely solar-powered system as opposed to grid power.

Green wireless internet is a spreading meme. The NGO Green Wifi is hoping to bring solar wireless to people in the developing world, a notion meant to dovetail with the $100 laptop. In NY, a group is selling pixels to raise the funds for a solar and wind powered system, while a handful of other cities (like San Francisco and Boulder) are wrangling with free-wireless-for-all legislation. Some are even working out back pack hacks, while others eschew wifi altogether. Folks in St. Louis Park will know on Nov. 6th whether their solar-powered wireless network is a green light. :: The Star Tribune via Hugg (Jetsongreen the incredible!)!