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Having used ENERGY 10 and other energy modeling software, and dealt with getting a home certified - I'd say it's bias and assumptions in the construction of the models, plus the fact that there is a base energy consumption per person that makes the percentage increase in a larger house not look as bad.
There are a number of stupid things in the Energystar and other ratings systems. For instance, I have some windows that don't conform to their ratings because the ratings were developed to be used across the country, with a bias toward both heating and cooling loads. I don't CARE about cooling loads, because we don't need to run AC for months at a time here. My house is designed to be passive solar, and I had to order special coatings on the windows (low E, relatively high SHGC) to get the passive solar to work right, but since my windows are not low E/low SHGC, we don't meet the standards.
Having used ENERGY 10 and other energy modeling software, and dealt with getting a home certified - I'd say it's bias and assumptions in the construction of the models, plus the fact that there is a base energy consumption per person that makes the percentage increase in a larger house not look as bad.
There are a number of stupid things in the Energystar and other ratings systems. For instance, I have some windows that don't conform to their ratings because the ratings were developed to be used across the country, with a bias toward both heating and cooling loads. I don't CARE about cooling loads, because we don't need to run AC for months at a time here. My house is designed to be passive solar, and I had to order special coatings on the windows (low E, relatively high SHGC) to get the passive solar to work right, but since my windows are not low E/low SHGC, we don't meet the standards.
I agree with this. While my 1700 sqft home was a HERS rating of 62 which is pretty darn efficent, it still failed to meet energy star certification, which has me very confused and I will have to look at this further on monday when I am at my work computer.
Rating systems aside, I know that when I've been in smaller homes (under 1,000 SF) I used far less energy for heating (the biggest issue up here in the North) than larger homes, despite the fact that the larger homes I've been in have all been more "modern" and well insulated. Still, that drafty little cabin (I think it was around 600 SF but that's a guess) with old single pane windows didn't take much to heat (small woodstove) and didn't take much to build either I'm sure. Just some thoughts FWIW. Perhaps it was in fact not as "efficient" per se as the larger and better insulated homes, but greater efficiency doesn't mean less resources used, necessarily.
A 6000sf house might be more "efficient" than a 1800sf house based on the HERS ratings. Just like a 25 cu ft refrigerator might be energy star compliant while a 3 cu ft fridge may not.
But it costs more in energy to run the bigger fridge, just like it would to run the bigger house.
A 6000sf house might be more "efficient" than a 1800sf house based on the HERS ratings. Just like a 25 cu ft refrigerator might be energy star compliant while a 3 cu ft fridge may not.
But it costs more in energy to run the bigger fridge, just like it would to run the bigger house.
yes, the 6000 sqft home is going to use more energy, but at the HERS rating they need to me all of the energy used is made on site, they have to be grid independent at that point. Boulder Colorado has the threshold set to 4500sqft and larger must meet a HERS index rating of 10, to get there you need very large solar arrays, most of which are more than enough to run the house off of. (15kw system on one 7000 sqft home) the utility company is going to be purchasing over produce from this client.
to get much lower than a rating of 80, more and more energy efficient things MUST be used, when you get to the thresholds you are living off grid, and producing what you need in terms of electricity.
Fewer solutions needed to clean it, too. Fewer materials needed to renovate if necessary.
I pay my trash hauling fees based on the size of my house -- smaller house, lower trash fees.
whaaa? Smaller homes are the majority of our renovation design work, people add larger additions to smaller homes than additions to larger homes.
Yes, wood is a renewable resource, therefore all homes made with such wood are being built with renewable resources.
My trash fees are not based on my house size, don't know why they would be, a family of 4 in a 1200 sqft home are not going to produce more trash then someone in a 6000 sqft home.
yes, the 6000 sqft home is going to use more energy, but at the HERS rating they need to me all of the energy used is made on site, they have to be grid independent at that point. Boulder Colorado has the threshold set to 4500sqft and larger must meet a HERS index rating of 10, to get there you need very large solar arrays, most of which are more than enough to run the house off of. (15kw system on one 7000 sqft home) the utility company is going to be purchasing over produce from this client.
to get much lower than a rating of 80, more and more energy efficient things MUST be used, when you get to the thresholds you are living off grid, and producing what you need in terms of electricity.
That's a code compliance issue rather than some inherent design feature of the bigger house, isn't it? The builders have to spend money to mitigate for the size of the house in order to meet the code, which seems to be designed to discourage the construction of large homes.
We should leave code compliance issues aside (since they are variable by location and thus not something that can be used to measure equivalence) and look at houses with similar construction methods.
Smaller houses use fewer materials to build. They contain smaller volumes of air that must be heated or cooled. That's going to cost less, both to the owner and to the environment.
That's a code compliance issue rather than some inherent design feature of the bigger house, isn't it? The builders have to spend money to mitigate for the size of the house in order to meet the code, which seems to be designed to discourage the construction of large homes.
We should leave code compliance issues aside (since they are variable by location and thus not something that can be used to measure equivalence) and look at houses with similar construction methods.
Smaller houses use fewer materials to build. They contain smaller volumes of air that must be heated or cooled. That's going to cost less, both to the owner and to the environment.
The HERS ratings are a code thing, but they are also a nationally recognized an industry standard way to calculate out the energy usage of a residence. A 10 hers rating in Colorado is the same as a 10 HERS rating in California or New York, it is not just a system in place where I design. The thresholds however are decided upon by the jurisdiction. the code compliance is a BIG thing, and should be accounted for when talking about efficiency. The code dictates what construction method is going to be used in a given design. I gave two examples earlier of homes built with very similar construction methods, same insulation values, same wood frame construction same framing methods, and same locations. They fared equal when the energy audit was conducted. yes, it may take more energy to heat and cool a larger house, but you DO have to take into account that most places that use the HERS rating or energy star rating systems will have these houses producing some if not all of their own energy, thus negating the taxation on the grid. Smaller houses do use less materials to build, but the materials used ARE renewable, thus Eco friendly.
you cannot just take out variables because they are not giving you the numbers you want.
Smaller homes are the majority of our renovation design work, people add larger additions to smaller homes than additions to larger homes.
If you add onto a small house, it's no longer a small house.
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