Posts Tagged ‘insulation’

Building a Home – Insulation

Posted on: October 22nd, 2012 No Comments

Cellulose bails on the insulation truck.

Before discussing insulation in new construction, it’s important to understand how it works. Insulation is used to limit the transmission of heat across a distance. For example, we try to limit how much heat is transferred into a home from the outside during summer months. Likewise, we try to limit how much heat we lose from inside a home during the winter. The thermal resistance of a material such as insulation is expressed in something called an R-value. The higher the R-value of a material, the better it is at limiting the transmission of heat. Video of insulation being blown into walls.

 

Close up of cellulose insulation.

Different materials have different R-values. Ideally, you want to balance the cost of the insulation material with the energy savings. In our case, the best application was also one of the most economical. Cellulose insulation consists of flame retardant organic fibers (i.e. recycled newspaper). Its thermal resistance isn’t quite as high as fiberglass or spray foam, but it is quite a bit less expensive. Cellulose is also very practical in the sense that, unlike rolled fiberglass insulation, it can be wetted and blown onto vertical walls and will fill small voids that rolled insulation can’t. Video of insulation being vacuumed and blown.

 

An exterior wall with blown cellulose insulation.

Insulation is only necessary in exterior walls (i.e. walls exposed to the outside of the house), though it may be desirable in some interior walls for noise reduction. Cellulose insulation comes in 18 pound bails. The bails are fairly compact and rigid, so they’re fed into a “grinder” that breaks down the bail and fluffs up the cellulose. It’s slightly wetted in the grinder so that it adheres to the vertical wall spaces as well as other cellulose particles. It exits the grinder into a hose from which it is blown out. After it’s blown into the wall, a crew member would run a scraper down the walls so that the insulation was even with the wall studs.  The particles that are scraped off the wall or don’t adhere are vacuumed and sent back to the grinder to be recycled. Video of insulation being scraped.

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Building a Home – HVAC

Posted on: October 21st, 2012 No Comments

Diagram of HVAC system.

You’ve probably heard the term HVAC before. It stands for Heating, Ventilation and Air Conditioning. Essentially, the system consists of a blower, evaporator, compressor and condenser.  When the system is running in “cool” mode, heat is transferred from the inside of the house to the outside. When it’s in “heat” mode, heat is transferred from the outside to the inside. There isn’t a separate unit for heating and cooling. Think of it like this: when you’re running your system in heat mode, it’s simply the air conditioner running in reverse. As a home owner, that’s all you really need to know about HVAC.

 

HVAC conduit being pulled up into the attic.

It took the crew installing our HVAC less than a day to do so. Most new construction has the air conduit installed in the attic. As such, it’s necessary to insulate the conduit so that your cool air isn’t being transferred into the attic. It was amazing to see the amount of insulation surrounding the conduit. A 6″ conduit actually measured about a foot in diameter with the insulation wrapped around it. Not only that, but the outside layer is a radiant barrier foil. All this is necessary to keep the HVAC system as efficient as possible. Video of air conduit being joined together.

 

A 6″ air conduit surrounded with insulation and radiant barrier.

The coolant for the system runs in an approximately 1″ copper line from the air handler in the attic down through the walls and out the back of the house to the condenser. Running the copper coolant line was probably the most technical part of the whole job. Unfortunately, I wasn’t there to get pictures of the air handler going up in the attic. The unit is too big to fit through the rafters pre-assembled, so they put it together on a platform in the attic. Similarly, if and when we eventually replace the unit, an HVAC specialist will have to disassemble it in the attic to get it out.  Video of coolant line being rolled out.

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