Do monster homes use more energy?
Published 4:00 am, Friday, April 18, 2008
The recent increase in the building of "McMansions" - extra-large homes that replace modest mid-last-century ranch homes and seem to swallow up an entire suburban lot - has long been controversial from an aesthetic point of view.
Now the overall environmental impact of large homes has come into question. At the heart of the debate is whether monster homes - dwellings larger than today's average of 3,500 square feet - use more energy than smaller ones.
Comparing the relative green qualities of a small home with those of a big one is complicated. How do you define the size of the homes? Are larger homes, because they tend to be newer, more efficient due to the use of state-of-the-art building materials?
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That said, even Pacific Gas and Electric Co. says that if Home A is one size and Home B is twice that size, Home B will probably use double the amount of energy.
The utility bases its conclusion on what's known as a Residential Appliance Saturation Study. It shows that multi-family buildings - apartments, condos and other dwellings that have shared walls - use less energy than single-family dwellings.
This isn't the same as comparing small homes against large single-family homes, but it does show that smaller dwellings tend to use less energy.
The study has a bright side for energy-conscious owners of newer homes, defined as those built after 1996. It shows that a new 2,039-square-foot home compared with an old 1,434-square-foot home - a 42 percent difference in size - uses only about 20 percent more electricity and 2 percent more gas. This is because of the use of energy-efficient construction and appliances.
It's also difficult to discount the energy hog factor - what difference does size make as far as energy consumption is concerned if the inhabitants are blasting five plasma TVs, three computers and a space heater in every room all day long?
But even when you eliminate that factor, some fixed costs associated with maintaining a dwelling are hard to get around.
Not surprisingly, chief among these are heating and cooling.
The ability to create zones within a house with separate thermostats for heating and cooling specific rooms may seem to solve this problem, but larger homes with unheated or cooled rooms can still waste energy.
This is because the rooms can easily become an "energy sink."
"Let's say you've got a whole guest suite with the guest bedroom and the bathroom and it's adding 3,000 square feet to your house, even if we do cut off the heat and the air conditioning to it ... there's still this big volume of room that is being placed in the sun," said green architect Eric Corey Freed, author of "Green Building and Remodeling for Dummies" and a principal with Organicarchitect in San Francisco.
"If it gets hot, it'll heat up the rest of the house and if it's one of those places that's always cold, it'll cool down the rest of the house. It can really work against us."
Freed said that many of his clients think a bigger house is the answer to their prayers. Persuading them to go with a smaller home is "the hardest thing to do because a lot of people don't want to give that up," he said.
"They feel entitled to having the gift wrap room and a pool room and a library, but how many times have you been over to somebody's house and everybody spends all their time in the kitchen? What we really need to do is just start planning our houses better," Freed said.
"If we know we're going hang out in the kitchen, let's design the kitchen the right way and maybe we'll make that bigger, but we can eliminate some other things."
The decision to think small is no longer optional in some communities such as Marin County. Since 2002, any new home or addition built in unincorporated Marin larger than 3,500 square feet must be designed to use no more energy than a 3,500-square-foot home.
Alec Hoffmann, green building coordinator for the Marin County Community Development Agency that oversees the program, said the law, now the basis for similar ordinances in Mill Valley, San Rafael and other California communities, saves money for home builders in the long run because it forces them to resort to more environmentally friendly elements such as solar heating - a move that earns them a credit toward achieving the energy footprint benchmark.
Hoffman said he's hopeful that the law will "drive the market for better contractor practices."
Marin's requirement, the first in the state, is based on the California Energy Commission's Energy Code - a complex calculation of fixed energy consumption associated with a home.
This is determined by feeding home energy use information on everything in a house - from the type of windows to heating systems to more obscure factors such as radiant barriers in the ceiling - into a computer model.
In other words, Hoffman said, "anything that uses energy in the house that's not something you plug in."
For the full report: links.sfgate.com/ZDAJ