Monday, August 11, 2008

The 'trades' move in

Well, it's been a while since the last official post and a lot has happened. I'll try to run though some of the important issues and get everyone up to speed.

The 'trades' (the plumbing, electrical, and mechanical contractors) will begin work this week...with plumbing going first, then electrical, then mechanical. Not necessarily the 'normal' order but our GC had some good reasons for doing it this way. This part of the project was a bit delayed from the original schedule due to a number of issues that are related to the masonry work (more on that later) as well as a few modifications to the plumbing and mechanical systems...a few of which are a result of our last LEED meeting and our desire to obtain a few extra points.

Electrical

This area has had the least amount of changes. The most important issue here is that we finalized most of the light selections. We needed to order all the lights that are recessed in the ceiling before the electrician gets started for, unlike lights like pendants and sconces that can be installed later, the 'cans' all need to be in place before the drywall is hung (which is still several weeks away).

One interesting item we discovered related to LEED points and lighting is that although we are already doing a lot in this house in the realm of energy efficiency, the lighting requirements (in order to get the max points, which is 3), are not as strict as we thought they would be. The prereq for this section requires installation of at least 4 Energy Star labeled fixtures OR install E.S. labeled CFL bulbs in the high use areas in the house. Since we have around 15 E.S. labeled fixtures and CFLs basically everywhere in the house, this was not an issue. Then there are two credit options - 1.5 points for installing 3 additional E.S. labeled fixtures AND using motion detect or p.v. for outside lights OR 3 points for installing E.S. labeled light bulbs in 80% of the home and using E.S. labeled ceiling fans. We are doing all this and a bit more so we see no problem in getting the max points here. This was reassuring but at the same time thought they would have been a little more strict (not that we're complaining...we'll take what we can get!)

Lastly, we are looking into installing an "Energy Miser" in the house. Typically, a house is using only 70% to 95% of the electricity that is coming through the electric meter and ultimately showing up on the electric bill. An energy miser reduces the electricity used by increasing the building’s “Power Factor”– which improves its electrical energy efficiency. It is essentially a panel that is attached to the main electrical panel. It captures and stores energy that would otherwise be lost, and routes it back into your building's system. It also reduces 6,000 pounds of carbon from your building’s carbon footprint. They cost about $500 but you can get various energy rebates that can be up to $100 and it can ultimately save you up to 20% on your electric bill.

Plumbing

The biggest change we made with the plumbing is related to the supply lines but we have also been discussing fixture and appliance selections too (which we'll get to in a different post). Originally, the plumber spec'd out PVC (polyvinyl chloride) for the supply and drain lines in the entire house. We immediately raised a red flag and stated that we do not want (if possible) any PVC in the house. In case you didn't know...PVC is a toxic carcinogen and releases dioxins (an extremely dangerous compound) when produced and when burned. So a few weeks ago we had the plumber price out the alternatives for us - which are copper or PEX (cross-linked polyethylene) tubing for the supply lines and cast iron or (possibly) polyethylene pipes for the drain lines.

Copper:

Although copper is the most trusted material for water supply lines (and plumbers swear by it), there are a few major drawbacks to using it these days: First, even though some percentage of the copper you buy off the shelf has recycled content, some of it will inevitably come from the mining process, which is environmentally devastating. Second, copper pipes need to be insulated (usually just the hot lines but LEED requires both hot AND cold pipes be insulated...this obviously involves an additional amount of material. Third, there is a lot of soldering involved as it comes in stock lengths and even a straight run often needs multiple connections, and additionally, every turn needs to be welded, which means there is a lot more labor involved. Which ties into the last drawback, it's just very expensive these days due to the high demand and short supply in the construction industry. As much as I respect the devotion of 'old school' plumbers, this material simply does not make much sense to use anymore.

Cast iron:

Cast iron is regarded in the plumbing industry similar to the way copper is. It really is one of the best solutions for drain pipes. BUT it has many of the same drawbacks that copper does...the most important one being cost. Let's just say we'd be paying almost three to four times as much to have cast iron pipes.

PEX:

[From the Plastic Pipe and Fitting Assoc. website] "Developed in the 1960's
, PEX tubing has been in use in many European countries for plumbing and was introduced in the US in the 1980s. PEX 's flexibility and strength at temperatures ranging from below freezing up to 200 degrees Fahrenheit makes it an ideal piping material for hot and cold water plumbing systems. It is flexible, making it easy to install and service. PEX is able to withstand the high and low temperatures found in plumbing and heating applications, and is highly resistant to chemicals found in the plumbing environment. Flexible systems are quieter than rigid piping. The smooth interior will not corrode which can affect other materials long term pipe flow characteristics. PEX systems have fewer joints and are easier to install providing a lower cost installation over traditional plumbing materials. " So as you can see, there are many advantages to using Pex including the fact that it is so easy to install many homeowners who are building simply run the supply lines themselves. Also, there is no need for all that pipe insulation since the tubing is already insulated. It is also by far the most cost effective solution.

As far as the manufacturing process of Pex...as I understand it, there are basically three ways:

The Engel process, where the cross linking happens "hot" (in its amorphic state above the crystalline melting point) since the polyethylene, anti-oxidants, and the cross linking initiator (peroxide) are extruded under pressure while in a molten state.
The Silane method, where a vinyl silane agent is added to the resin/polymer base prior to the extrusion process, thus forming a grafted copolymer.
The Radiation method, which involves bombarding previously extruded PE tubing with Gamma/Beta electrons while sealed in a vacuum chamber

Not sure yet which is the 'greenest' process (my instinct would go with either the Engel or Radiation method) nor do I know if we will even have a choice in the matter. I just figured it was good information to know.

Basically, the system works as follows: In the basement, there is a "manifold" that ties into the water heater and main water supply. This has a bunch of pairs of connections (red for hot and blue for cold). The amount of connections pairs depends on the amount of fixtures you have. Separate flexible red and blue pipes run from the manifold all the way to the fixture (uninterrupted). The pipe makes "bends" instead of turns which is actually more efficient than 90 degree turns (like copper) in relation to pressure drop. There is an open/close valve at the manifold too that let's you easily control the supply.


















PEX piping and manifold

Up to now I have been told that there really isn't any other alternative (other than cast iron) to PVC as far as drain lines are concerned. BUT, through some research I found that they do make a rigid polyethylene pipe that can be used for drain lines. I need to find out a bit more about this and then get a price difference from the PVC drain lines before we make a final decision. Obviously this would be a great solution for it would eliminate virtually all of the PVC plumbing in the house.

So as you might suspect, we have decided to move forward with the PEX system (for at least the supply lines at this point). But as with any product that is new to me, I start my web search with "Problems with ____", and see what comes up. The only real negative story I found was someone reported that they thought rodents seeking water had gotten into their floors and ceilings and chewed through the pipes and thus caused some leaks. This was never really substantiated, but the way I see it is that if you have rodents running through your floors and ceilings...you have bigger problems to deal with.

Mechanical

The unit we chose is the Goodman 14 SEER 92% Efficient furnace and a 3-ton rooftop A/C unit.

The main change regarding the HVAC system is related to LEED points and the SEER
(Seasonal Energy Efficiency Ratio) rating and HSPF (Heating Seasonal Performance Factor) of our unit. SEER rating is the Btu of cooling output during a typical cooling-season divided by the total electric energy input in watt-hours during the same period. HSPF is a ratio of BTU heat output over the heating season to watt- hours of electricity used. The higher the SEER and HSPF, the more energy efficient the system. Originally, the mechanical contractor had spec'd a 13 SEER / 8.2 HSPF unit. This is a good unit but only satisfies the pre-req for LEED. We needed to upgrade to a 14 SEER / 8.6 HSPF unit to get 2 points for using a "High-Efficiency" system. I have not gotten verification but I would speculate at this point that the cost difference is somewhere around $500...giver or take a few hundred. It's a good thing to do regardless, as jumping up even 1 SEER saves a pretty decent amount of energy when it comes to heating and cooling.

Another thing we are verifying (and what will be tested) are the "distribution losses" that are caused by leaks in the ducts and poorly insulated systems. Our mechanical contractor is now aware of the values (measured in cfm) that we need to achieve and assured us that it would not be a problem. The less cfm lost, the more efficient the system, and the more LEED points we'll achieve (up to 3 if we do well.)


What's next? The next task at hand is for us to complete our "Durability Risk Evaluation Form" (which we began a while back but never finished) for LEED which is part of the "Durability Management Process". But more on that later.

2 comments:

Andrew said...

I know PEX piping is banned by code in some California cities (in very modern code - updated within the past 3 years), but without rationale. I'm wondering if you might have any insight into why that might be, and if in fact PEX is code-compliant in Philadelphia.

Southern Liberties, LLC - Phila, PA said...

Andrew...I did hear that PEX was banned in some parts of California (which surprised me) but from what I can see it is not due to any flaw in the product. In my opinion, it's the work of a very powerful plumbers union that does not want to change and does not want PEX on the market. You see, if an inexpensive and easily installable material was to flood the market, they could not continue to charge the enormous rates they currently do. This may not seem ethical but it is a 'rationale'.

As I mentioned in the post, plumbers love copper and cast iron (which are undoubtedly great for plumbing) but the materials are expensive and difficult to work with. Enter...a cheap material that any homeowner can install and you have some serious job security on your hands. Unions are tied to politicians which in turn influence lawmakers. Sound corrupt? It is, and frankly, I am surprised that it isn't banned in Philadelphia - which, by the way, it's not. PEX is totally acceptable to use here...for now, at least.

Thanks for the comment.