Energy Efficiency for Builders, The Why. Part 1
Fall is one of the seasons that homeowners often think about keeping their houses warm and keeping the operating costs down. Once the home is built it can get tricky and complicated at times. But that is existing homes. For a new home we want to build well right from the start .
To give a little perspective, when we look at the broader view of energy efficiency, the US ranks near the bottom. The American Council for Energy Efficient Economy reports in the International Energy Score Card* that out of 16 of the largest world economies , the US is near the bottom at 13. This is across all energy sectors, but when looking at Buildings alone it is not much better. “ The United States –long considered an innovative and competitive world leader – has allowed other nations to surpass it” the report states. We can do better, we need to walk the talk now and step up and be the leader with home efficiency. Because we lag, it is a new industry to us. Investment in this will stimulate jobs as we all say we need to do. On a smaller perspective what this can do is create a competitive edge for builders. I have long said that the new home buyer is a discerning buyer that wants to know “what kind of mileage” are they going to get with their new home. Building efficiently is the next direction.
So how do we do this ….
Building tightness and airflow.
There are many things that we currently do, some well, many not. First let’s answer that age old issue about building a tight home. Yes a house needs to breathe, but do we need to live in a barn? With the most common energy code, the 2009 IECC, the minimum threshold is a max of 7 air changes per hour. I have tested many homes that could make that limit. Some cannot though. If you could feel the air moving through the house, you would understand that 7 ACH is a fairly low standard to reach. 7 ACH is a lot of air. Most homes being built today can reach this and better. Now, making homes tighter is more efficient, BUT we must consider a few things in this.
I have said to homeowners after the fact, you can put all the energy upgrades you want in the house. If you don’t pay attention to the structure, the shell of the home, you are just wasting energy more efficiently! We need to seal the home up.
Back that nagging question about living in a tight home. It has been long documented that if you have a tight home there is a separate set of issues that need to be addressed. In certain instances a tight home can make indoor air quality suffer. That could mean in ways of indoor air pollutants, off gassing of products, moisture is a big contributor. To deal with these pollutants, we need to ventilate. There are three means to do this; some are more costly than others. And likewise some are more effective than others.
1. Supply only strategy is when you have an inlet in to the return plenum prior to the filter from the outside. It must have a damper. In the mid-Atlantic area this is not recommended. It doesn’t get the pollutants out and it dumps a small amount of 100% unconditioned air into the system.
2. Exhaust only strategy is a preferred method often utilizing upgraded bath fans. They are programmable and can run continuously at a small amount from the bathroom, usually the point source for the moisture contamination. Broan Nutone have some great fans for a reasonable price depending on the features you get. Some of the basic silent fans are about $145 and up. Again remember you are building a tight efficient home at this point, ventilation is needed, this will take care of the off gassing of materials and vent excess moisture and help insure it is a safe place.
3. Lastly is the “Cadillac” strategy of an Energy Recovery Ventilator (EVR) or a Heat Recovery Ventilator (HRV). These are units that sit adjacent to the heating unit and draw a small amount of fresh air from the outside and inside at the same time. The air is exhausted through a heat exchanger where it tempers the incoming air. The efficiency of these can be in the 70% range. As you can imagine these units are costly, often $2000 and up installed. The advantage is that they draw air from all points of the house, not just a point source like a bathroom and they do not waste as much energy. The differences between an HRV and an EVR are subtle but important and deal with moisture and each are better suited to specific climates. One is better in far northern climates than the other. An HVAC professional can help with choosing the one for your buildings.
Some of these strategies and practices you may currently use. Perhaps some are not standard for you. . However there are incentive programs in PA that offer consulting and guidance as a resource for you, the builder. There is the Penn Residential Energy Codes Initiative* . Which provides an opportunity for a free limited ResNet HERS Rating* for those that have not been introduced to the HERS System. You can have a complimentary Rating that identifies ways that you can improve your homes. Then it can provide factual information on operating costs as well as much more information about the performance of the house. It includes complimentary site visits and testing as well.
For those that are familiar with a HERS rating, the utility providers in PA have programs designed to account for the increased energy savings you have built into your homes as compared to a Code Built home. A Rating is performed and the energy savings are calculated in KWH. Depending on the utility, you can get $0.10 per kwh with First Energy*, and $0.30 per khw with PPL*. But you will need a Rater to certify it. All electric homes are best suited for these programs. Geothermal homes should strongly consider these programs as well. Rebates can reach $2000 in some cases.
Stay tuned for more How To in the next issue.
*Check these sites for more information;
American Council for Energy Efficient Economy http://aceee.org/portal/national-policy/international-scorecard
Penn Residential Energy Codes http://pennenergycodes.com/
ResNet HERS Rating System http://www.resnet.us/energy-rating
First Energy New Homes Program, http://www.energysavepa-newhomes.com/
PPL New Homes https://www.pplelectric.com/save-energy-and-money/all-rebates-and-discounts/residential/new-home-construction.aspx
For more information contact a Rater today.