Monthly Archives: December 2013

plumbing and wiring

2013 12 19: most of the plumbing and the wiring are completed.

although not shown in the picture, there are three colors of wire used in the house. yellow wire is 12 gage and goes to all the outlets. this is somewhat unusual. excepting the kitchen and bathroom, most outlets in most houses are a lighter gage, 14. the white wire is 14 gage and goes to light fixtures. orange wire is really heavy gage and goes to the point of use hot water heaters and the dryer.

the picture also shows some orange pipe. this is used to provide water to a sprinkler system.

plumbing and wiring

plumbing and wiring

the energy recovery ventilator and the heat recovery ventilator

2013 12 19: the energy recovery ventilator (erv) and the heat recovery ventilator (hrv) are installed. these are appliances that exhaust stale air from the house and replace the air with outside air. when it is cold outside, they do this so that the heat from the exhausting air is transferred to the incoming air with the opposite happening when it is hot outside.  in principle it would be like passing the exhaust air through a radiator core while the incoming air flows through the fins; but this is not the configuration that the units employ.  the efficiency of the heat transfer is remarkably high. zehnder, the company that supplied my units, has an hrv that is 93% efficient. the erv also transfers humidity, which is especially helpful during maryland’s humid summers, keeping the dryer air inside dry even though humid outside air is coming in.

i purchased zehnder hrv and erv from aubrey gewehr of zehnder america. aubrey provided excellent sales and technical support on what i believe are the best available hrvs and revs. if you have an interest in these units he can be reached at 603-422-6700 or at www.zehnderamerica.com

if you contact him, i believe you will be pleased.

in my application, the erv is used to exhaust stale air from the house and replace it with fresh air. i understand that this is a necessity in my house because it is so tight. if this were not done, carbon dioxide could build to an uncomfortable, perhaps even an unsafe, concentration.

the hrv is used differently than usual to solve a bit of a dilemma. leed requires that the air above the cooktop be exhausted to the outside at a minimum rate of 100 cubic feet per minute. we were not able to find any valves that could tightly close the exhaust duct to the outside. in addition, to do this in such a tight house requires make up air; again with no valve available. so we thought to use a kitchen hood from the vent-a-hood company, http://www.ventahood.com, in conjunction with the hrv. this hood normally recirculates air. it is special in that it actually removes grease and smoke from the air. this is in contrast to most recirculating hoods, which are minimally effective at best. we will not use the hood in recirculating mode, instead we are ducting it to the hrv in the hopes that the exhaust from the cooktop will be cleaned enough that it will not foul the hrv. the hrv will also provide make up air. so far as we know, this will be the first time such an arrangement has been employed. wish us luck.

the first picture shows the erv. to its right is the geothermal heat exchanger. it is connected to a loop of tubing in which an anti-freeze solution circulates and which runs under ground. so the incoming air temperature is passed through a heat transfer that is at 55 fahrenheit, the ground temperature in maryland in both summer and winter. overall, this improves the efficiency. it also prevents freezing at the erv air intake during the winter. the large grey tube exhausts the air. on top of the erv is a muffler and manifold. on top of the manifold are white ducts that either exhaust air from the bathroom and kitchen or send air to the living area and bedrooms. the second picture is a wider view of the equipment. the third picture shows the air supply from the erv in one of the bedrooms. the fourth picture is the hrv.

the erv showing exhaust and supply tubes

the erv showing exhaust and supply tubes

 

 

 

 

 

 

 

 

the erv and ground loop box

the erv and ground loop box

 

 

 

 

 

 

 

 

 

a source of clean air from the rev

a source of clean air from the erv

 

 

 

 

 

 

 

 

 

the hrv

the hrv

 

 

water efficiency

2013 12 17: mary sper and lauren wheeler of natural resources design, inc., 202-489-6214, have put together a very water efficient landscape for the house. mary predicts the outdoor water usage for the site to be 47,487 gallons per month.  leed baselines the outdoor usage at 179,574 gallons per month; i suppose as a sort of norm. quite a reduction!

the indoor usage is also very low. the toilets use only 0.8 gallons per flush, and each bathroom is equipped with waterless urinals, low flow shower heads and low flow faucets. the kitchen is equipped with a low flow faucet and a very efficient dishwasher and the laundry room uses a very efficient washer.

at the end of it all, we are predicting, using leed methodology that the house will save 134,907 gallons per month from the base-line. leed says this is exemplary performance. of course, this will have to be verified by the leed rater but i think we’re looking very good in this department.

appreciation

2013 12 11

brooks grasso did a great job of arranging a construction loan for the house. he and the columbia bank’s mortgage division, fulton mortgage company, were pleased to offer a loan on my old hopkins road energy efficient and environmentally benign house. this was in startling contrast to some other banks. not only that, our build did not start anywhere near the date we provided; because of this we ended up way behind schedule. fulton mortgage took this in stride and made effective arrangements to overcome the problem. i could not be happier with brooks and the mortgage company.

brooks is extremely knowledgeable, very responsive and very helpful. i’ve taken the liberty of presenting his contact information from a scan of his business card and included copies of a few of his awards. if you’re in need of a construction or other home load, he’s the one.

like all of my appreciations, this is unsolicited and i receive nothing for it.

a really helpful person

a really helpful person

 

 

the shed is erected

2013 11 26 the garden shed is up. it is in back of the house and has a slanted roof for solar panels. the three panels that will go on its roof supply electrical power to a hot water heater. i prefer photovoltaic solar panels to solar thermal collectors because i believe they are more reliable and less troublesome to install.

it is somewhat unusual to have them directly power a hot water heater and a bit less efficient than letting them feed power to the grid connected house circuitry. it came about because the roof on the shed originally was to have solar thermal collectors. this fell apart when the manufacturer we had selected quit making the collectors.

the shed is up

the shed is up