Tag Archives: energy

2nd floor on demand pump

My current modus operatus is wrapping up loose ends. This includes the installation of the on demand hot water pump on the 2nd floor. But this time I did it with confidence, because I had the installation experience from the 1st floor under my belt, including a correction.  And I had the helpful hands of our friend Rubani assisting me.

What is this on demand hot water pump all about? Here is the super short version:

The on demand pump is activated through the push of a button. It pulls water from the hot water line and pushes it into the cold water line. Once the pump senses a rise in the water temperature, it shuts off. This primes all fixtures on the hot water branch the pump is connected to, effectively cutting the delivery time of hot water to seconds.

The on demand hot water pump is just one piece in the puzzle of an efficient domestic hot water delivery system. If you haven’t caught my earlier posts on this system, let me provide you a brief summary with links:

When you are in your bathroom or kitchen and turn on the hot water, do you have to wait for a minute or two (or longer) for the hot water to arrive? Is so, you do not have an efficient hot water delivery system. An efficient delivery system cuts the wait time for hot water to arrive to a few seconds, as mentioned above.

And it does more: It reduces water waste and as such helps with water conservation. It also results in material conservation, as the ground rule for an efficient domestic hot water delivery system is a compact layout and smaller pipe sizes (made possible through the water conservation efforts).

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You find that in an efficient domestic hot water delivery system all pipes are insulated and that it effectively manages structural and behavioral waste of hot water, which again feeds into the water conservation mentioned above.

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An efficient hot water delivery system relies on structured plumbing rather than the traditional trunk-and-branch layout. With a structured plumbing system, the on demand pump is placed at the end of the one hot water branch that services all fixtures.

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Fanning over efficiency

There are several useful tools in the cyberworld that can assist with making energy efficient decisions. One of those tools is the Energy Star website with its Product Finder section.

But there is also a cautionary tale here – hidden in the fine print, if you will. I recently ran into this head on, while looking into ceiling fans.

One of the big home improvement stores had a sale on ceiling fans that I wanted to take advantage of, because it included a number of Energy Star certified products. I went to the Energy Star Product Finder to look up the performance specifications of the fans that were currently on sale.

Well, the dichotomy between ceiling fans that meet the minimum efficacy levels and ceiling fans that seem light years ahead of those levels is quite remarkable!

The minimum efficacy levels set forth in the product criteria are as follows:

  • At low speed, fans must have a minimum airflow of 1,250 CFM and an efficiency of 155 cfm/W
  • At medium speed, fans must have a minimum airflow of 3,000 CFM and an efficiency of 100 cfm/W
  • At high speed, fans must have a minimum airflow of 5,000 CFM and an efficiency of 75 cfm/W

A ceiling fan sized 43” to 60” meeting the above criteria, in addition to the luminair requirements, will carry the Energy Star label. And most of those fans may exceed those standards by a factor of about 1.3.

Yet there are ceiling fans on the market that leave those requirements in the dust. Take the Emerson Midway Eco (CF955) that I researched and purchased for our 1st floor:

  • At 561 cfm/W at low speed, it is 3.6 times more efficient than the minimum requirement
  • At 475 cfm/W at medium speed, it is 4.75 times more efficient than the minimum requirement
  • At 336 cfm/.W at high speed, it is 4.5 times more efficient that the minimum requirement

On the extreme end, the Home Decorators Collection – 60in Aero Breeze at 1447 cfm/W at low speed, exceeds the minimum requirements by a factor of 9.3.

Bottom line: Look for the Energy star label on products, but don’t buy just yet! Do your research first, because there may be a product that blows those Energy Star requirements out of the water – and saves you money down the road.

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2016 heating savings

It is friggin cold outside, and I can’t shake the urge to keep talking about heating related matters, so here we go again:

One goal of our deep energy retrofit was to save energy, and along with it, some Benjamin Franklins. The money we invested in tightening and insulating the building was meant to save us dollars on our heating bill, for instance.

But how would we measure how much we save? Our problem was that we had no starting point. We bought our building as a foreclosure in 2009 and thus had no data – no access to utility bills – that would tell us what it took to keep the building heated and comfortable.

That said, there are plenty of buildings in our neighborhood that could serve as a comparable (comp). Not only are they the same construction type, but also in the same energy deficient shape as our building was before we started with our deep energy retrofit.

I found a building that was a good match, and the owner that was happy to share their utility data with us.

To compare apples to apples – or in this case, therms to therms – I calculated the amount of therms used per square foot per month for both buildings. Our building’s natural gas consumption is reflected in the blue bars, while the comp, or pre-retrofit state, is reflected in the red bars.

Data reflections

Why is there natural gas used during the summer months (off heating season)? Because in both cases natural gas is used to produce domestic hot water, i.e. washing the dishes, running the washing machine on warm or hot cycle, taking a shower, etc.

You may have seen me bragging about turning our heat on as late as mid November. If you look at the consumption for November 2016, you see that we mostly used domestic hot water while our neighbor in the comp building had the boiler already buzzing away.

Looking at the big picture, our building consumed 0.200 therms/square foot over the course of one year, while the comp usage was at 0.976. Our deep energy retrofit improvements appear to have reduced our natural gas consumption by 0.776 therms/square foot/year. That equals a reduction in our heating needs from November 2015 through December 2016 by a whopping 80%!

For our metric friends (i.e. the world with the exception of the U.S.): Our natural gas consumption equated 63.04 kWh (or 226.95 MJ) per square meter, while the comp came in at 307.89 kWh (or 1108.39 MJ) per square meter.

I typically don’t like to measure the improvements in cost savings, as supply cost and taxes may vary between jurisdictions or energy companies. In addition, the fixed costs on the gas bill, although often small, prevent accurate scaling to a square foot basis.

Yet getting an approximation of the monetary savings would give us a sense of the potential return on investment. We paid $0.27 for natural gas per square foot over the course of a year. The cost of the comp were $0.98. The estimated total cost savings for the 2,900 square foot of conditioned space in our building from November 2015 through December 2016 would be in the range of $2,000.

Yes – I am beaming right now! Yet, this somehow seems too good to be true. I think the flaw with my analysis is that I have based it on one comp only. I plan to find another couple of buildings that I could include in the analysis. That should give me a number that would be easier to defend.

Stay tuned, because I will keep you posted!

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Welcome waste (energy)

Today, we are not pinching nickels, but degrees.

I mentioned in the last post that it took us until November 17 before we turned the heat on, whereas other Chicagoans fired up their furnaces in early October. Why were we still comfortable several weeks into the cold weather?

Waste heat!

Boiling the kettle, cooking dinner, baking banana bread … Then add in all the electrical appliances that produce waste heat: running the fridge, TV, laptop and desktop computers, having the lights on … all this and more produce some level of waste heat which is welcome during this season. Not so much during the dog days of summer, though.

But wait! There’s more. Let’s not ignore the four critters occupying the space. Two of them two legged, and the other two four legged. Believe me, they all have a healthy metabolism going, based on the heat they throw off! Seriously, body heat from building occupants is not to be ignored – not in the context of a deep energy retrofit.

Let’s think of these heat sources as miniature radiators. Individually, they don’t do much. But cumulatively they begin to matter, if – and this is a big IF – the building is well insulated  and as good as airtight. Because now this waste heat doesn’t escape. It lingers around and keeps the building interior at a comfortable temperature when others have long reached for their thermostats.

In this context, your furnishing and the actual interior of your building begins to act as a heat sink – it becomes thermal mass. Your oak dresser, your hardwood floors, your drywall, your bathroom tiles, you name it – they all store heat to some degree, which adds to the comfort.

Another gadget that helps us to delay the start of the heating season in the Energy Recovery Ventilator (ERV). It delivers fresh air into our airtight building envelope, but does so with the help of a heat exchanger. This allow us to recover most of the precious waste heat and yet still get fresh air.

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How did I miss this?

On a deep energy retrofit like ours, the clock is always ticking. Not only was it ticking, recently the alarm went off too: I have known for a number of years that I had till this year (2016) to install renewable energy components and claim the juicy 30% Residential Renewable Energy Tax Credit.

pv-panels-01

We are interested in a photovoltaic and solar hot water system. Knowing that the time to claim the tax credit was running out, I took the first steps of organizing the project and was surprised – pleasantly surprised:

The tax credit has been extended. With limitations, but still, it has been extended.

The government actually got something done! Wouldn’t you think that’s BIG news? I can’t believe that I missed this.

“Note: The Consolidated Appropriations Act, signed in December 2015, extended the expiration date for PV and solar thermal technologies, and introduced a gradual step down in the credit value for these technologies. The credit for all other technologies will expire at the end of 2016.”

Source: Energy.gov

The good news: The Residential Renewable Energy Tax Credit for photo voltaic and solar hot water system was extended until 01-01-2022.

The bad news: The Residential Renewable Energy Tax Credit for fuel cells, wind turbines and geothermal heat pumps is still running out at the end of this year (2016).

“A taxpayer may claim a credit of 30% of qualified expenditures for a system that serves a dwelling unit located in the United States that is owned and used as a residence by the taxpayer. Expenditures with respect to the equipment are treated as made when the installation is completed. If the installation is at a new home, the “placed in service” date is the date of occupancy by the homeowner. Expenditures include labor costs for on-site preparation, assembly or original system installation, and for piping or wiring to interconnect a system to the home. If the federal tax credit exceeds tax liability, the excess amount may be carried forward to the succeeding taxable year. The maximum allowable credit, equipment requirements and other details vary by technology, as outlined below.”

Source: Energy.gov

But – the clock is still ticking. Here is more fine print: If you would like to claim 30% of the Residential Renewable Energy Tax Credit on photovoltaic and solar hot water, you have until the end of 2019. From 12-31-2019 till 01-01-2021 the tax credit for systems placed in service is reduced to 26%. And for systems placed in service between 12-31-2020 and 01-01-2022, the credit is further reduced to 22%. Once you’ve missed this last deadline, you are left hoping for another extension.

You can access details about the Residential Renewable Energy Tax Credit here:
http://energy.gov/savings/residential-renewable-energy-tax-credit