Saturday, May 10, 2008

energy efficiency improvement for renters

some of the easiest and most cost-effective ways to reduce energy consumption are modifications to your residence. for people who own their place, this is fine. they can replace their appliances and water heaters with more efficient versions as the old ones fail or become cost-inefficient to continue using. many cities even have incentive programs to help pay for the cost of improvements. for anyone who rents, though, there seems to be little we can do.

it seems to me that most rental units are maintained on a least-cost basis. the old, inefficient water heater won't be replaced until the cost of maintenance is greater than the cost of replacement. generally, the renter pays for the electricity (or natural gas) to run the heater and few renter ask about what type of water heater an apartment has before signing a lease so the owner has little financial incentive to replace the unit with a more efficient one.

even though renters cannot replace the main electric water heater, there may be an alternative: ask the landlord to turn it off and install simple point of use tankless water heaters instead.

old style water heaters are inefficient because they keep a large volume of water hot all of the time. this large volume of water is kept in an insulated metal cylinder. the energy efficiency rating of a water heater is largely determined by the quality of the insulation. no matter how good the insulation is, some amount of heat will always leak out either through the tank's insulation or the insulation on the pipes from the water heater to the residence's various outlets. this wasted heat is wasted energy, which means extra greenhouse gas pointlessly being produced and money being thrown away.

tankless point of use water heaters eliminate these storage and transmission heat losses by heating the water only when it is needed and in a location directly adjacent to where it will be used. they can be no more difficult to install (or uninstall) than a brita faucet-mount water filter, plug into a normal electric socket, and leave no marks on the property (so the landlord shouldn't care). the hardest part would be convincing your landlord to turn the old water heater off.

if you assume the apartment has the oldest, most inefficient water heater the landlord can keep running (a pretty safe assumption from what i've seen), you could reduce your energy consumed to heat water by 25%. according to one estimate, you could save $125 per year. considering that the devices only cost about $100 per faucet, they'd pay for themselves pretty quickly. plus, there are the added benefits that the water is immediately hot (so less water is wasted waiting for the cold water to flush from the pipes), there is as much hot water as you want, and the water temperature won't fluctuate when somebody flushes a toilet. this is a simple way for renters to reduce their household carbon consumption.

for the sake of being boring, i'd like to mention also that electric utilities are going to hate these things if they ever become popular. they will take a nice, simple to model base load device that operates 24 hours a day and turn it into a peak load that goes from 0 to 2kW instantly when people shower or use their sink. so, less energy will be consumed (which means less income for the utility) and the peak power consumption will increase (which means higher infrastructure cost for the utility). best of all, many states have energy efficiency promotion requirements that force utilities to help subsidize this sort of energy efficiency improvement. so the utilities are forced to encourage people to pay the utility less while costing the utility more. what could be funnier?

also worth noting: where i live, electricity is basically free (it takes serious effort to spend more than $80/month on electricity), so these things would never pay off unless the residence uses a natural gas water heater.


leila said...

i believe everything you say. do we have a gas water heater? and are we going to do this?


Tom said...

When I went to Colombia the B&B I stayed in had one of these for their shower, however a little sophisticated. The bare wires sticking out just above a showerhead drenched in water, while I stood below with my feet standing in water made me wonder why a steady electrical current was not running through me. We also had one of these on a oil-fired furnace in the home in which you were born. It fired up as soon as the small storage tank cooled. This is really nothing new, just newly packaged and hopefully more efficient.

shaun said...

if i had to guess, i'd say we probably won't do this in the current place, since we plan to move soon and the next place will probably have an electric water heater

shaun said...

the wires didn't electrocute you because clean freshwater is a pretty poor conductor. if you had ever touched the wires and the metal drain simultaneously while your skin was saturated with water, though, that'd be a different story.