A conventional water heater typically uses natural gas or propane to heat a tank of water that’s anywhere from 40 to 80 gallons in size. The drawback of this design is that the water heater is constantly keeping that water hot (so its ready when you need it).  In addition, once the tank has been depleted, there’s no hot water until the water in the tank is re-heated.  So the 3rd shower of the morning might be a cold one.

Today you have a few choices:

Tankless Hot Water Heater:  A tankless heater can be electric or gas but only gas heaters have the capacity to serve an entire house.  With this type of hot water heating, you only heat water when you need it — saving the cost of storing and heating hot water when not in use.  The estimate of cost savings vary widely depending on the efficiency of your existing hot water heater and whether it’s insulated.  If you have an efficient, insulated tank, the savings might be as little as $100/ year making a long payback period.  Consumer Reports looked at the issue and concluded that the energy savings doesn’t pay for the increased cost over the life of the system.  Some families find that costs actually go up because they take longer showers. 

There are other problems with Tankless heaters.  First, it’s not “instant hot” – hot water won’t get to your faucet any faster unless the distance to the faucet is lessened.  will still take .  Second, you can’t trickle hot water – Tankless heaters require a minimum flow rate to provide hot water.  Third, they heat the water up by a number of degrees – the colder the water going into the tankless heater; the colder is the water coming out.  So you if you live in an area with big differences in seasons, you might be frustrated with a sense that the hot water is erratic.

Tankless heaters, though, can be a great back-up for a house that usually has only 2 occupants but might have 6 or more occupants for summer months. 

Tankless with Small Tank:  Many of the problems with a tankless system can be solved by adding a small tank (maybe 8-10 gallons) on the output end of your tankless system.  Make sure the tank is very efficient and well insulated and many of the problems of the Tankless system can be eliminated.  This does not change the payback period. 

Hybrid Tank:  Many companies that make Hot Water Heaters now offer what’s known as a Hybrid Hot Water Heater.  They’re essentially standard electric water heaters but with a small heat pump unit on top that utilizes room air to heat the water as much as possible. They do have elements to cover high-demand periods, but offer a number of settings to meet demand and/or minimize energy consumption.  Most of what I’ve read suggest that the monthly savings is much greater than with a Tankless system.  They fit into the same space and with the same connections as a standard hot water heater making installation relatively easy with most homes.   For an all electric house, this choice seems to be a good one. 

Solar Hot Water Heater:  Hawaii has become the first state to require solar water heaters in new homes. Other areas with high number of sun-days like Arizona and Florida also have a high proportion of solar hot water heaters. 

solar hot water collector next to photovoltaic array

Solar hot water systems have two parts:  a rooftop collectors (shown above) and a storage tank with built in heat exchanger. The solar collector is usually made up of copper tubes and a copper plate that is covered with a highly selective absorber coating; this assembly is enclosed in a well-insulated aluminum frame and covered with low-iron tempered glass glazing. A propylene glycol solution within the copper tubes is heated in the collectors and circulated through a heat exchanger located in the bottom of the solar storage tank. The household water contained within the storage tank is heated by the solution circulated through the heat exchanger. The propylene glycol solution is gradually heated by the sun’s energy which is transferred to the solution in the collectors. Reliable automatic controls operate a circulation pump and provide optimal solar water heater system operation.

The solar collectors have to be installed on a roof with at least at 15% pitch.  The ideal orientation for the solar collectors is due south. The collectors can be rotated from south, up to 45° east or west with minimal loss in solar heat gain.  Solar water heaters are always installed with an auxiliary heat source, or in addition to your regular electric or gas water heater. That means that even on cloudy days they will still have hot water. To maximize their savings, homeowners should attempt to use the most hot water in the late morning and early afternoon when the solar system is operating at its peak.

Payback for a solar hot water heater may be up to 10 years without any tax incentives. 
Instant Hot Water:  While you’re talking with your plumber about replacing your hot water heater, also talk with him about what system is right for your home to provide faster hot water at the faucet.  In many homes, you have to run the water for 30 seconds before you get water hot enough to take a shower or wash your hands.  You can install systems either a loop in your plumbing system that circulates hot water back to the hot water heater.  If this isn’t possible, another alternative is a recirculating pump.  These products employ a temperature actuated by-pass valve that connects the cold and hot water supply lines at the fixture that is farthest away from the water heater. The bypass valve uses the cold water line as the return loop back to the water heater.  This change can save lots of water that would otherwise go down the drain while you wait for hot water. 
First Things First
And of course just like other energy savings measures, you can save lots of water and energy by taking simple steps before you place your hot water heater: 
– Turn the thermostat down. Many water heaters are set to between 140 and 180°F (60 and 82°C). See how low you can go. Try 125°F (52°C) for starters. A hot tub is 106°F (41°C). How much hotter do you need?
– Wrap the water heater with insulation. Insulated water heater “blankets” are usually available where water heaters are sold. (Be careful with natural gas or propane fired water tanks. They use an open flame to heat the water. You need to provide a space for air at the bottom of the tank, and at the top where the flue exits the tank. Safety comes before efficiency!)
– Fix those drips. They may not look like much, but they are a constant and persistent drain on your water heating load, and they waste water too.
– Use flow restrictors and faucet aerators to reduce your hot water consumption.
– Find other ways to use less hot water. Wash only full loads of clothes and dishes.
– Insulate your hot water pipes.

Our conversation got me thinking about the mid- and longer-term future of “green” remodeling.   This article is partially  prediction and partially day-dreaming.

ON-SITE ENERGY PRODUCTION. The rapid development of new photovoltaic technology is truly exciting.  I think we’re still a few years away from it being truly practical and affordable for most residential remodeling projects.  However, there are two developments that I think will lead to practical application to existing homes:
- Photovoltaic glazing and cladding material.  The roofs of existing housing stock are rarely oriented to capture optimum solar energy.  But every structure has a south facade.  When glazing and cladding materials on the south facade can capture sunlight and convert it to energy, we’ll start to see a real break-through in on-site energy production from the existing housing stock.

Solar Ivy - The Answer to Residential Energy Generation?

- Innovative ideas such as Solar Ivy.  The image, above, is of “Solar Ivy” crawling across the south facade of a city brownstone.  It’s one of the truly exciting ideas I’ve read recently.  “Solar Ivy” is a grid of individual solar collectors – that appear almost like vines of ivy growing up the side of a building.  This technology is particularly appropriate to the scale of existing residences — it is added-on after the structure is complete and it has a scale that’s appropriate to existing residences.  I believe that I could even get it approved in the Historic Districts around Washington, DC where I often work.  Read more about Solar Ivy.

MICRO-REGION DISTRIBUTED ENERGY PRODUCTION. As truly renewable energy collection increases in efficiency and decreases in cost  – both wind and solar – businesses will be able to generate more energy than they use.  Since business peak usage is often the reverse of the residential peak usage times, we’ll have the potential of much finer grid optimization.  With office structures more often located close to residential communities, we’ll reduce the load on our transportation system while increasing the potential for efficient locally distributed energy production.

THE END OF THE LAWN WARS. Our suburbs – and too often our cities – have houses surrounded by lawns.  I’ve seen too many men succumb to the siren song of the perfect green lawn.  And what accompanies the green lawn is very high water usage plus the use of fertilizers and pesticides that pollute our rivers and lakes.  Higher water prices and regulatory changes designed to protect increasingly scarce potable water sources will hopefully put an end to the Lawn Wars as well as encourage pedal operated faucets, rain gardens, native plantings, and denser development.   All of these changes also reduce energy usage and our carbon footprint.  That’s the beauty of sustainable practices — you get a really big bang for your buck!

DENSER DEVELOPMENT.  Sprawl is the enemy of sustainable and green development.  I cringe when I see 5000 square foot second homes in rural settings achieve LEED or other “green” certification.  There is absolutely nothing green about a house of this sort.  It might have been built with technology that reduces huge energy and water consumption to more manageable levels but it is definitely NOT green.  Similarly, I am not outraged as some of my neighbors are when a single family home on a large lot close-in to a city is replace with 4 or 6 town-homes.  Instead I applaud the better use of our resources and the reduced load on our transportation systems.  That is not to say that I want the character of our existing close-in neighborhoods to change dramatically.  Indeed, it’s usually these close-in neighborhoods that have more modest homes on smaller lots.  And they have sidewalks and close-by shopping and services that encourage walking and discourage the use of cars and encourage a sense of community.

MODULAR REMODELING SYSTEMS. Prefab housing  is all the rage with many residential architects.  While the theory might be sound – that building in a factory reduces waste – it just doesn’t seem to save money.  I can stick-build an addition for less than I can purchase it as a prefab unit.  Plus, I get something more appropriate to the existing home.  But I do think that with rapid advances in building materials, we’ll start to see better applicability of modular systems to the existing housing stock.  For example, I think, that in the relatively near future, we’ll see spray foams that in addition to providing better insulation will improve structural integrity, stop rot, kill mold, and even form a usable interior cladding – replacing drywall.  We’ll see lighter-weight and stronger beam and other structural members that will enable us to completely open-up the interior of a building allowing for temporary walls – so that we can remodel a home as easily as we can reconfigure a commercial interior.  We’ll be able to preserve the character of the neighborhood and even historic exteriors while providing for a modular interior that costs much less to reconfigure for changing family needs..

TRANSPORTATION.  Energy-efficient and non-polluting transportation systems are critical to green building.  Our technology should already allow us to be able to walk a short distance from our door in the city or suburbs and then be transported quickly and efficiently to within blocks of our desired destination.  What’s stopping our advancement in this area – and I believe also in energy and building systems – is our entrenched industrial structures.  30 years ago I had a conversation with one of my brothers about the future of transportation.  If non-traditional transportation companies had been worrying the problem in the past 30 years we would be there now.  We need companies where innovation and problem solving are part of their DNA – companies like Apple or 3M or HP — to start working on solutions to our energy and transportation problems.  Detroit and traditional transportation companies have shown that they don’t have the answers.  We need to encourage the answers to come from elsewhere.  For one such idea, look at an Article in Metropolis by Paul Makovsky.

For additional stimulation, I also recommend another series in Metropolis for more reading about the near, mid and long-term future of technology.

Icicles - Dramatic Demonstration of Heat Loss

Compare Your House To Others in Neighborhood

The house, above, is an exaggerated example of heat escaping and prematurely melting the snow that’s accumulated on the roof.  Look at it compared to the house next door.  You can look at your house compared to others in your neighborhood.  Be careful to consider exposure – the snow on a south facing roof on a sunny day will melt much more quickly than on a north or east facing roof.  The pattern of melting can also give clues about where the leaks are coming from.  Remember, all the warm air escaping to melt the snow is being replaced with cold air coming in!

Lots of folks in old houses think that replacing their windows is the most important step to cure drafty, cold houses.  In fact, windows are quite low down on the list of areas for improvement.

Here are some rules of thumb:
1.    Seal all drafts first. They are the biggest winners, while conversely if you don’t take care of them they’ll undo the effectiveness of any other improvements. Many of the biggest ones are hidden; for instance, the vertical chase of each “wet wall” (space for pipes behind your tubs and showers) is usually open to the attic.

Next go from top to bottom.

2.    The attic is a huge area and usually the easiest area to install insulation or adde-to existing insulation.
3.    Next improve weather-stripping & sealing of windows and doors.  Good storm windows plus weather-stripping and sealing of windows brings them almost on par with new windows – at must less cost.
4.    Garage walls (insulate and drywall) and door (insulated unit) if you have rooms above.
5.    All of this comes before adding insulation to walls – it’s the hardest and most expensive to do.   However, if you’re planning on replacing your siding, that’s the perfect time to blow-in insulation from outside into the wall cavities and to add a layer of foam board sheeting to the outside walls.
6.    Last in effectiveness is under-floor insulation.

Finally, I must confess, that the house pictured above is mine!  When I bought the home, I planned an immediate remodel and figured I would take of everything then.  But the economy has shifted the remodel back in time.  It is well past time to make some necessary improvement – which I can promise you will be done before the end of the winter.  First on the list is sealing leaks, second is attic insulation, and third is to replace my storm windows and repair the broken sash cords and weather strip the existing windows.  And I’m sure that next winter will be much more comfortable than this winter.  I’ll reap the financial rewards of a better sealed and insulated home during both the heating and cooling seasons.

If you’re stuck inside and want to read more about saving energy & money, click here, for a free US Dept of Energy Booklet on the subject.