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Building a Light Green LEED House in Houston, TX
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Projected energy usage and HERS rating for our green house in Houston

Amidst all the selections, pricing estimates and getting final decisions made in many areas, we are also getting some very exciting projections related to the energy efficiency of the house.

As background, our choice to go with regular stick-and-frame construction, as compared to SIPs or even concrete shells, was driven by budget. In Houston, stick-and-frame is remarkably affordable, making it hard to go another route, when you are trying to get to around $150/sq ft. The major concern was that stick-and-frame would limit how much can be achieved in energy efficiency. Current projections suggest that you can still get a pretty good HERS rating, and low energy costs with our approach.

To offset the choice of construction, we opted for a simple rectangular house shape, which gives you a good ration of volume to shell, making it inherently energy efficient. Then we positioned the windows out of the direct sunlight, and shaded them where possible. Add a metal roof, some good insulation, a sealed attic and you can get pretty far. 

The HERS Index rates your house, just like Energy Star rates your appliances. You can read about HERS Index here. In summary, a HERS rating of 100 is the standard new home, in terms of energy consumption. A rating of 0 would be off the grid - a house that consumes no energy, by producing its own. Most existing homes are above a 100. Our '50s bungalow, with $500+/month a/c bills in the heat of the Houston summer is probably well above 100. Right now our estimate is below 60!! 

This is very exciting, and will also result in additional LEED points. When doing LEED scoring, in the energy efficiency category, you can use HERS ratings to get a simple LEED point number. Our original estimates was at HERS 77, giving us 8.5 LEED points. Now we may gain more than twice that. Hmmm... This puts LEED Silver in the bag, and has been an impetus to look to see whether we can go further.

In dollars and cents, this also has an impact. We got a first estimate of the energy costs of our house - see below - and it is below $2,200 for the year. This is electricity only, which is heating and cooling and appliances. (Water heating, cooking and the dryer will all be gas.) This year, to date, we have already paid over $3,000 with one more month to go. And the projections are at 16 cents/KwH while we are paying around 13.5 cents for our renewable energy plan. So, taking that into account we could get as low as $1,850. So, our 3,200 sq ft new house might have 60% of the electricity cost of our 1,900 sq ft '50s scape off. 

(download)

Filed under  //  HERS   LEED  
Posted by Oliver Bogler 
 

LEED for Homes Reference Guide - searching for more points for our house in Houston

The LEED for Homes Reference Guide came last week, and this morning I had some time to sit down and read it. By read, I mean go over the section intros and read some of the parts in depth. It is quite long, and just a tad dry...

I mainly focused on the areas where our preliminary assessment appears to leave room for more points.

Here is the big picture: LEED is a point system, with some prerequisites and then points depending on how green you can go. There are 8 categories in which you can earn these points, encompassing everything from what you build to how you build it and spread the word. There are different categories, depending on how many points you get.

For our house, which will come in around 3,200 sq ft, we need 51 points to gain Certification (the basic level) and 66 to gain Silver. Our preliminary assessment by our architects puts us at 59.5, so well within the basic, and tantalizingly close to Silver...

You can see our preliminary assessment here:

Click here to download:
LEED assessment.pdf (114 KB)
(download)

In some areas we are getting lots of points. In others we seem to be leaving lots of points on the table, in particular in the SS Sustainable Sites, WE Water Efficiency and EA Energy and Atmosphere areas.

In the SS and WE the assumption is that we install a high efficiency irrigation system, perhaps with water reuse. We will also landscape with local, drought resistant plants and add some trees. At present we do not have an irrigation system and do not water our yard, front or back. It gets a little dry in the summer, but not so that you would notice it overly much. We do not have real grass, but a local ground cover that does well. So, if we install no irrigation system at all, we may well gain points, as our water use should be low compared to the typical house in the area. Currently our annual consumption is around 50,000 gallons.

The big one is the EA category - we are currently programmed to gain only 10 of 38 points, and 8 of 34 of the Optimize Energy Performance category. In EA you can either go through a global assessment, using the HERS system, or section by section. We are going to do the former, so we will learn much more when we have our preliminary HERS assessment. The 8 points here are for a HERS of 72 - with better windows, and a higher SEER rating on our A/C we may get higher, and earn more points.

In total we need a projected 6.5 points over what is already in the plan. It seems that with no irrigation and careful landscaping, we may gain 5 there alone. With a good HERS score, we may well earn another point or two. Perhaps Silver is not out of the question.

Big caveat: $

Everything has to fit the budget. October will tell us more, as we get the price projection once the schematics are complete. That said, leaving out the irrigation system will actually save money!

Filed under  //  HERS   LEED  
Posted by Oliver Bogler 
 

Squeezing the sq ft, Elevation Certificate, Engineer, HERS - our #LEED house - #greenbuilding in #Houston

It has been a busy house week, and the pace is beginning to pick up now! Here is a quick summary:

We saw a first draft of the plans for the second floor. Here is a schematic, with some suggested edits by us (can you guess which one will be our daughter's room?). This part sits over the first floor leaving the rear sections (part of the kitchen and the family room) without a second floor. So we are getting very close!

However, the total sq ft is a little higher than our target. We discussed the connection between sq ft and cost with our builder, Michael Strong - www.greenhausbuilders.com - he explained that different areas of the house have different costs, depending on plumbing, built ins, materials. Kitchen and bathrooms are expensive. Bedrooms are relatively cheap. In any case, our architects - Kathleen Reardon and John Dazey - www.rdarc.com - are looking at squeezing some sq ft out. One possibility is combining the library and family rooms. 
Top-floor-v1-option-1

We had a meeting with Michael Strong about a variety of things - which we are getting busy on: 

1) First up is an Elevation Certificate, to see how high we need to build to get us well positioned for future floods. We have ordered the survey for this for next week. 

2) Then we learned that we need to hire an engineer, who will primarily focus on the foundation. Apparently in our situation we have a choice between pier and beam and slab, with no strong factors tilting us either way. Of course, a solid foundation is going to be critical. We do have a significant amount of ground movement here, and although we have not had any catastrophic foundation damage, you can see our concrete behind the house cracking pretty nicely. 

3) We discussed HERS as well - Home Energy Rating System - which is a measurement of how energy efficient the house is. It takes into consideration everything from insulation to the kinds of systems you have, such as air conditioning. It is calibrated so that the average house is 100, and one that is off the grid is 0. You need to get to 85 or below to be an energy star house. While not directly connected to LEED, there is clearly an overlap in factors that are considered. We are going to find a HERS professional to help us make the assessment, once the plans are complete.

Sample_hers_report_page_1_of_2

4) We are beginning to talk to trades too - the many subcontractors in the business. I met with Aveon this week - www.aveon.com - they do home system integration for security, control, entertainment. I learned that pre-wiring, especially for the ground floor, is a very good idea. If you think you may need it, it is better to put it in during construction, rather than try to do it after. On our current house the brought the cable into the front room by drilling through the outside wall...  Anyway, Aveon sell the Control 4 system - this is all new to me - but it is pretty amazing. Killer: you can control your a/c and tv from your iPhone. Seriously, I'd love a system where we can listen to music in various places, have good control of the temperature and good security too.

We are also going to talk to a A/C contractor. This is Houston, after all, so that is a top priority.

5) Selection List - the big piece of homework heading our way is the selection list. This is a multi-tab spreadsheet of all the things that go into the house, and we will be heavily involved in making these decisions. And of course, budget is always part of the picture. 

We also touched on the timeline of the whole project with Michael - we still hope to break ground by January and complete the building next year! So we are probably 14 months out, from moving in.

Filed under  //  HERS   architect   builder   planning   plans   trades  
Posted by Oliver Bogler