Posts Tagged ‘thermal envelope’

DIY: Home Energy Audit -The Building as a System

Thursday, June 30th, 2011

Your house works as a system. When one part isn’t working properly, the whole house doesn’t function correctly.

Remember when I said when mama isn’t happy, nobody is happy? This is pretty true for the house as a system, too. It is like when the air conditioner isn’t size properly, and it is pushing too much air out or when there is a gaping hole in the basement and air is escaping through it, and you don’t understand why it is always cold right above that spot in the dead of Winter… See- your house is a system, and it knows when something is awry. Conducting your systems check during your home energy audit will help address these issues! Here are some of the features you need to look at to ensure that your home functions as a healthy system when you do your own home energy audit.  You may have heard about people having Home Energy Raters(HERS) crawling around their houses with sophisticated tools and equipment blowing smoke here and there and everywhere, what is this stuff even doing anyway? Well, more than likely, these energy auditors are testing to see where there is air leakage from the home to outside of the home. We call this air leakage to the outside of the envelope. Let’s identify some of these things so you know what we’re talking about moving forward:

Thermal Envelope- The great people from the City of Seattle framed it quite nicely when they put together a really awesome DIY home energy audit package a few years back. We totally agree with them that “the first step in an energy audit is to understand where the boundary is between the heated and un-heated spaces in your home. This boundary is called the building enclosure, or shell. It includes the walls, ceilings and floors between the inside and the outside, as well as those between heated and un-heated spaces, such as a garage or basement. In a simply shaped home it may include just four walls, a ceiling and floor, but most homes are more complex. A heated floor becomes a porch floor, or a side attic connects to a wall. Bay windows have tops and bottoms, and skylight wells must be insulated, too. It may help to make a sketch similar to the one shown, identifying the specific configuration of your home.”

Air Leakage- This is super important to take a look at since air leakage accounts for much of our energy loss in our homes,- they say more than 1/3 of our energy loss if through air leakage!  “Since warm air rises, a heated home in winter acts like a big chimney. As the warm air rises and escapes through ceiling penetrations, cold air is pulled in from the basement, garage, or crawl space. The cold air can bring dust or pollutants with it as well as make our homes more dry, since moisture escapes with the warm air and the cold air coming in lowers the humidity in the space. Any penetration in the building shell will result in air leakage. Along with doors and windows, obvious places where cold outside air enters a home are penetrations for heating ducts, water pipes, sewer stacks, wiring, lighting fixtures, electrical switches and outlets, chimneys, ventilation fans, attic hatches, fireplaces and pet doors.”

Windows- Take a look around your window frames, make sure they are sealed with a nice continuous bead of caulk. Quite obviously, you will want your windows to be free of damage and cracks. Make note of any damage to your windows and feel for any drafts. If you need to weather strip the windows, now is the time to make note of this.

Doors Frames- Just like your windows, you want to feel around the frames for drafts. Check for any missing weatherstripping and make notes on what needs to be fixed or replaced. Make sure your doors don’t open to a room that is heated such as a garage or a room that can pull in toxic gases. This also goes for little doors for your pets.

Insulation- Talk about super-important for the thermal envelope! “Insulation slows the transfer of heat from the warm side to the cold side of a wall,ceiling or floor. Its purpose is to keep heat in during the winter and out during the summer. Placing insulation between living spaces and unheated areas produces a protective shell around your home. Insulation products are rated by their resistance to heat flow, called R-Value. The higher the number, the more effective the insulation and the lower your energy bills. Most homes in the United States built before the 1970’s are poorly insulated, if at all. Modern energy codes require minimum levels of insulation. To see if and how well your home is insulated you will be going to each area of your home’s envelope – walls, floors, ceilings – and looking at both the type of insulation installed and its thickness. Some areas may be easy to see, such as insulation in an
attic space. In other areas such as walls, you will need to probe behind the surface. If you are unable to determine the insulation type and/or depth, such as in a flat roof or cantilevered ceiling, professional insulation contractors and energy raters will be able to
investigate further with laser thermometers or an Infrared scanner. If your attic has no opening, you should make one yourself or have a contractor do it for you.”

Now that we’ve talked about what your preparations, your tools and now the house as a system, we’re going to look at the mechanical system of the house before we move on to how to inspect the spaces. We want you to be prepared to see what you’re going to see and know how it all operates together- as a happy little system! Stay tuned and let us know if you have any questions.

Arlington Based Architect Greens It at Lecture Series

Tuesday, April 5th, 2011

The Green It Series with the Arlington Green Home Choice Program featured speaker Marta Layseca of EnviroHomeDesign at last night’s lecture series at the Arlington Central Library.

Arlington County has a very strong green building community and they keep it so by hosting community based lecture series such as the one hosted at the Central library last night featuring award winning architect Marta Layseca of EnviroHomeDesign. The series topic focused on the retrofitting of existing homes which are being remodeled in the Arlington area. Marta spoke on the importance of bringing together a team of professionals to review the existing conditions of the property, assess the requirements of the design and the specifics of the clients’ needs for functionality, the certifications needed to become a truly green built property and the homeowners own verification.

There were two case studies in which Marta highlighted, and Eco-Spanish Colonial and an Eco-Brick Colonial, both homes were requiring retrofitting and remodeling to different levels, but Marta and her team were able to bring these homes to higher green standards through ensuring that the homes thermal envelope was properly sealed, the mechanical systems were properly addressed and that the resources and design were addressed not only with the homeowner but thoughtfully considered through passive design. Marta spent quite some time discussing the concept that window frames in the US are not insulated window systems and that this causes a lot of energy loss. Having a third party verification system such as EarthCraft, Marta advocates is a great way to ensure that the home is sealed properly at pre-drywall. “Energy conservation strategy, especially at the windows and at the concrete foundation and insulation of crawl space and attic creates a thermos.”

What Marta means by creating a thermos out of the home is that, once you have created a very tight thermal envelope, there is a point at which fresh air needs to be introduced into the home to create a mechanical system that is healthy such as an energy recovery ventilator, or ERV. Both homes in her case studies presented had ERV systems and both were tightly sealed. The client who lives in the Eco-Brick Colonial property was at the lecture to participate in discussion: “At first I was skeptical; I wasn’t ever sure what we could even do regarding a green home… but now we absolutely love where we live.” Regarding the ERV system, she states  that it is “nice to have the fresh air coming into the home… it even smells fresher.”

The other systems such as energy efficient resource selection, i.e. the high heel trusses,  high fly-ash concrete, grey-water tanks for flushing the toilets,  and many other eco-friendly selections were discussed in more detail. The fact that Marta creates beautiful, functional, healthy homes which make her clients happy was almost appeared as  a side note to the high performance features and systems that go into these award winning homes in this discussion.