Natural Resource Canada’s Office of Energy Efficiency shows the average amount of energy used by each of these appliances (Natural Resources Canada, 2009):

Using 1990 as a baseline, appliances in the average home in Canada used 5,789 KWH of energy annually:

Energy consumption can be reduced significantly through the use of Energy Star appliances. The following provides an example of what could be accomplished using some of the more highly rated appliances available (U.S. Environmental Protection Agency):

* Electric ranges and clothes dryers are not rated as part of the Energy Star program because there is little difference in energy use among models. We have used the Natural Resources Canada energy use statistics for 2006.

Using more efficient appliances (Energy Star where applicable) can result in a 49% decrease in energy use. When you purchase new appliances or replace your existing appliances, close consideration should be given to purchasing the most energy efficient EnergyStar rated appliances.

]]> http://www.vereco.ca/blog/2010/12/09/energy-efficient-appliances/feed/ 0 http://www.vereco.ca/blog/2010/12/02/drain-water-heat-recovery-%e2%80%93-an-effective-way-to-reuse-thermal-energy/ http://www.vereco.ca/blog/2010/12/02/drain-water-heat-recovery-%e2%80%93-an-effective-way-to-reuse-thermal-energy/#comments Thu, 02 Dec 2010 22:50:33 +0000 admin http://www.vereco.ca/blog/?p=117 Drain water heat recovery (DWHR) is a relatively simple technology to reuse household hot water energy and to prolong the availability of hot water during periods of high demand or continuous use.

In 2007, CMHC completed a study (07-116 Canada Mortgage and Housing Corporation, 2007) on this technology. CMHC explains that DWHR units take advantage of the fact that as water drains it clings to the sides of vertical drainpipes due to surface tension. This creates a very high surface-contact-to-volume ratio, allowing heat to be recovered from the drain water by wrapping the incoming cold water supply pipe around the vertical drain.

Figure 1 – CMHC drawing of Drain Water Heat Recovery System

In most homes, drain water will come in three types:

• Hot – from dishwashers, showers, bath tubs
• Cold – from toilets
• Hot or cold – from clothes washers and sinks

The steadiest source of  hot drain water will come from showers, as the hot water is continuously entering the drain for the duration of the shower. The other important feature to note about drain water from showers is that this drain water is produced simultaneously with hot water requirements, since the shower is using hot water at the same time as the DWHR system is reusing the energy from the hot water going down the drain.

The study evaluated two different configurations. In the first configuration (A), the DWHR system was connected to the hot water heater. In the second configuration (B), the DWHR system was connected to the hot water heater and the cold water tap on the shower.

The savings for a typical family of 4 was significant. The following is a subset of the results of the study and shows the savings for the most effective DWHR unit tested (PowerPipe R60) in kWh/year.

Figure 2 Annual savings in kWh/year

The savings are significant, given the relatively low cost of installing a DWHR, its long useful life, and the fact that it will require no maintenance once installed.

CMHC tests suggested (07-116 Canada Mortgage and Housing Corporation, 2007) that the benefits from delayed hot water requirements was minimal. The study came to several interesting conclusions:

• ‘Although the devices are very similar, the performance of comparable units can vary widely based on the way in which the soft copper tube is shaped and then wrapped around the drainpipe section.

• The efficiency and effectiveness of DWHR units is lifestyle dependent. Households with high shower use will obtain more benefit from installing a DWHR unit than households where baths are more prevalent.

• Households in rural areas without access to a municipal water supply will need to look at units that have designs that minimize reductions in water line pressure.’

A DWHR system is a good investment. The energy savings are significant and the DWHR has a long useful life with little or no maintenance. The system will extend the availability of hot water during periods of prolonged use, allowing the home owner to install a smaller water heater.

This article talks about the personal experience of the author with a tankless water heater over the last ten years.

What is a tankless water heater?

As the name suggests, a tankless water heater provides hot water without the use of a storage tank. Also called an “inline” water heater or a “demand” water heater, these units heat the water as fast as it is used. The change in temperature from the input to the output takes only a few seconds and is constant, in my case more than 90 degrees F. The Saskatoon city water arrives at my home by underground pipe at about 40 degrees F (a little cooler in February) and, depending on how much cold water I mix in at the tap, is plenty hot enough for any use I have. The burner in the water heater has, at 120,000 BTUs, a higher rating than my furnace, at 110,000 BTUs. The water heater burner only cuts in when a hot water tap is opened somewhere in the house. The water heater senses the pressure drop when water is flowing to a hot water tap or appliance such as the dishwasher.

What is the biggest advantage?

The biggest advantage of a tankless water heater is that there is no stored water to keep hot. There is also no pilot light consuming natural gas, even when you are away. The only time natural gas is used is when someone is using hot water somewhere in the house. For the record, when only using hot water with no other natural gas appliances in use, such as the furnace, my natural gas bill is around $25 per month (in summer 2010 I had 2 months like this) and this includes all the fixed fees SaskEnergy charges that don’t depend on usage.

What is the biggest disadvantage?

The biggest disadvantage in my case is that I use a little more water, although I haven’t measured the change between before and after. As well, because the tank was a retrofit, I had to put my tankless water heater in the basement where the hot water tank was before it. There is now a lag of about 15 seconds at the tap furthest from the water heater (the kitchen) before hot water is available. If it was new construction, I would arrange all hot water appliances to be close to the water heater and this problem would go away. In all fairness, with a conventional water heater, the first several seconds are lukewarm at best but no one ever looks at that aspect on a conventional water heater.

I hear there are things you can do now that you can’t do with a conventional water heater.

There are several things you can do with a tankless water heater. One of the benefits is you don’t have to wait for the water to heat up before a second or third person can have a shower. You can even fill a 450 gallon hot tub at a temperature of 104 degrees F (the hottest that is safe for a hot tub) instead of having to wait for the water to heat up once in the hot tub (or Jacuzzi). Everyone likes the continuous hot water so much that it’s common for people to stay in the shower just a little bit longer to enjoy it.

OK, so what about maintenance?

As I said I have had my tankless water heater for 10 years. I get it serviced once every two or three years. When the technician services it, he cleans it, and replaces a seal or two. It takes less than an hour. I never have any scale build-up this way, despite the fact that the water is quite hard in my neighborhood. At the 10 year mark the technician has now put in a “service kit” which he tells me should last another 10 years. The life of the water heater should be well over 20 years at this rate.

Servicing needs to be done by an experienced technician, as the water heater is a little more complicated than a conventional water heater. It’s not that it has a lot of moving parts (it only has a few moving parts), it’s just that the technician needs to know about venturis, and so on. I have stayed with the same plumber throughout the last ten years and have had great service.

The water heater is not hooked up to the house electrical service. It uses 2 D-cell batteries, which I end up replacing about every 1.5 years.

I hesitate to mention the make of water heater I have because it has been replaced in the stores by newer versions. My water heater is in the 80% efficient range, having come out before the high efficiency versions were available. I also never had the chance to use a rebate of any kind, also before they were available.

So, how do you decide what size of tankless water heater to get?

Tankless water heaters are rated on how many appliances they can source the water for at once. Mine is a one-appliance water heater. Newer versions can be bought that are designed for two appliances or more. Keep in mind that the BTU rating goes up significantly for a larger rating as well as the cost. My family of four used this one-appliance tankless water heater all through our childrens’ teenage years. With a few adjustments, everything went just fine. No one ever had to complain about our daughter using all the hot water. It was impossible to do.

To answer the question, think about how many appliances you want to use at once that use significant amounts of hot water. Consider making minor lifestyle changes to minimize this number. In practice a family of four very rarely uses more than one appliance at once.

What about washing clothes and dishes?

Clothes washers nowadays use cold water only when most efficient so there is no need for hot water for washing clothes.

Our dishwasher has a “heat the water” setting, which we use because of the 15 second delay to the kitchen sink. It doesn’t have to do any heating after the first 15 seconds. The other setting we quite often use on the dishwasher is the 2 hr delay before starting so that any showers are done before the dishwasher asks for hot water.

So where did you learn about tankless water heaters?

I first used a tankless water heater in Brazil about 25 years ago when I was on assignment for the company I work for. I was there for 6 months. The tankless water heater was really tiny and was right beside the sink. I felt it was undersized as the water was never really hot, but realized it had to be really inexpensive to run. When it was time to replace my water heater 15 years later, I made the leap and have never regretted it. Tankless water heaters were barely available then in Saskatoon but I expect they will become more and more popular as the word spreads and as energy costs rise. They have been quite common in Europe for many years.

Have you any tips on installing one?

Put the hot water tank and the hot water appliances as close together as possible to minimize the delay for hot water.

One thing you will find is that the water pressure on the hot water tap is a little less than the water pressure on the cold water tap. This becomes important on taps that you rotate to go from cold to hot water (i.e. where the hot and cold water come out of the same tap). The effect is that you will have a smaller rotation range for hot than for cold. One way around this is to install a small pressure reducer on the cold water just after the Tee that goes to the hot water heater. This will keep the pressure the same on hot and cold. The other solution is to use separate taps for hot and cold water so the pressure difference doesn’t matter.

I don’t recommend discussing the technical details with the sales staff unless they actually have used one for themselves. Sales staff with experience in tankless water heaters are fairly rare so far, although I expect this will change.

House temperatures are typically controlled by a programmable thermostat or in the case of older homes, manual adjustments to the thermostat. I always remember my father nagging us to ‘turn the thermostat down’ when we were going to bed or leaving the house for the day.

There are a number of programmable thermostats readily available. The typical application is to ‘set back’ the temperature during winter days when residents are at work and overnight when residents are sleeping and to ‘set forward’ the temperature during the same periods on summer days.

This is a relatively simple and low cost technology that virtually anyone can apply to any existing home. I was very curious to see how significant the savings would be.

CMHC, in their study Effects of thermostat setting on energy consumption (05-100 Canada Mortgage and Housing Corporation, 2005) determined that significant savings could be achieved. Tests showed that various night and day set-back/set-forward (11:00PM to 6:00AM and 9:00AM to 4:00PM) resulted in the following savings:

Temperature setting can have a significant impact on energy consumption for both winter heating and summer cooling.  CMHC completed their tests in very energy efficient homes and still realized significant savings of 13% of winter heating costs and 23.3% on summer cooling costs.  You could realize even greater savings if your home is not as energy efficient.

This simple low cost technology is easy to implement, saves money and reduces energy consumption and green house gases immediately. Everyone should be doing it.

REFERENCE

05-100 Canada Mortgage and Housing Corporation. (2005). Effects of thermostat setting on energy consumption . Ottawa: CMHC.

• Domestic hot water – energy used to heat water for day to day use in baths, showers, washing, etc.
• Space heating/cooling – energy used to heat or cool the home.
• Appliances – energy (usually electric) used for lighting, appliances, and mechanical.

A typical Canadian home uses between 25~33% of their energy heating domestic hot water. The easiest way to reduce the energy you use heating hot water is to reduce the amount of hot water you use.

In their 2004 booklet on Water Conservation, Carbon Dioxide Reduction Edmonton identifies a number of strategies available to reduce the amount of water and more specifically hot water used:

• Repair any leaking faucets
• Install low flow shower heads
• Install low flow faucet aerators
• Purchase Energy Star clothes washer and dish washer.

A leaking faucet dripping only one drop per second will waste 8000 litres of water per year. If this is hot water, the cost is even more significant. Repairing any leaking faucets is an easy and cost effective way to save energy.

Low flow shower heads will reduce hot water usage by 30 to 50% without significantly reducing the feel of the shower. These are inexpensive to purchase and easy to install.

Figure 1 – Source CORE : An inexpensive flow restrictor and be installed to reduce the water flow rate by 20~30%

Low flow faucet aerators thread into existing faucets. They reduce flow rates by up to 50% by mixing air into the water. This can translate into overall water savings of 30% on a typical faucet.

Front loading Energy Star clothes washers will use 30-50% less water than regular clothes washers. They also do a better job of extracting water from clothes during the spin cycle which will further reduce energy costs related to drying clothes. Energy Star dish washers use at least 25% less water and can save 20% on heating costs by heating incoming water.

So what are we waiting for? Proven technologies are available to reduce hot water consumption in your home. Reducing hot water consumption will reduce the amount of energy you use, save you money and lower your green house gas emissions.

Looking at out greenhouse gas emissions helps us understand where we fit into the picture — and in fact, what we can do to change. The Conference Board of Canada (www.conferenceboard.ca) ranks Canada very poorly in the area of greenhouse gas emissions:

‘Canada is one of the world’s largest GHG emitters. Canada ranks 16th out of 17 OECD countries on GHG emissions per capita and scores a “D” grade. In 2005, Canada’s GHG emissions were 22.6 tonnes per capita, almost double the 17-country average of 12.4 tonnes per capita. Canada’s per capita GHG emissions were also almost four times greater than Norway’s, the top performer.

While Canada’s GHG emissions per capita have risen since 1990, Norway managed to decrease its GHG emissions per capita by 30 per cent between 1990 and 2005.’

Figure 1 – Canada Conference Board report card on Canadian Green House Gas emissions

I have lived in Saskatchewan all of my life. I always thought of us as a green, environmentally friendly society. It came as a big surprise to me that Saskatchewan is actually the second highest greenhouse gas emitter in the world. According to the Saskatchewan Environmental Society (www.environmentalsociety.ca) we are at 72 tonnes per capita. This is nothing to be proud of. We typically blame our climate but Scandinavian countries like Norway, Sweden, Finland and Denmark have similar climates and they are doing much, much better than we are (see Conference Board of Canada report card above)

Residential energy use accounts for 16 per cent of total energy use in Canada. But there are ways to reduce this impact. For example, if we look at the Riverdale Net Zero Home (see my November 11, 2009 blog),  the average home in Saskatchewan would  be responsible for nearly 17 tonnes of greenhouse gas emissions per year.  This assumes an R2000 construction standard.  Of course, most new homes are not built to the same green standard, even though it’s possible.

So what are we waiting for? Proven technologies are available to eliminate or minimize energy use in residential housing. Reducing your energy use clearly saves money and reduces green house gas emissions. We need to start using these technologies to do our share for the environment. We need to build green.

Mark and I both found the home quite attractive in a unique way. Mark (18) commented; ‘Cool – I would love to live in a house like this.’

A lot of Net Zero homes are criticized for their appearance. The challenge is usually with the placement of solar and PV panels. The Riverdale Net Zero home in Edmonton is an example of a home that was challenged with the need to put the solar panels on the front of the house.

I have heard a lot of controversy over this design. I have toured the Riverdale Net Zero Home and it actually looks quite attractive and fits in with the very modern architecture of the homes in that area.

Other Net Zero homes look like any other house on the block. The Mill Creek Net Zero Home is an example:

The back yard of this home faces south so the solar panels are all located at the back. If you look carefully at this picture, you can spot the solar panels on the roof at the back but other than that, you would never know that this is a Net Zero Home.

The CHESS net zero home in Red Deer used a different strategy and integrated their solar panels into the roof line. The solar panels are visible from the street but more integrated into a standard design:

As you can see, NetZero homes come in all shapes and sizes. The variable appears to be the cost of one design over the other. Please take a moment to let me know your thoughts on these 4 designs: Which would you prefer to live in? All are Net Zero Homes but the Michelle Kaufman home would be significantly more cost effective (probably 25% less per foot than the others). Would that affect your decision? You can contact me at ronn@ronnlepage.com.

The Building Saskatchewan Green conference was in Saskatoon last week. Although I could not attend the entire conference, I did get a chance to attend the Friday luncheon and visit the expo.

I always find the expo to be the most interesting. I feel I can get a sense of what is happening in the market by who is at the expo. The following are some of my observations:

• There were 3-4 solar hot water companies. All of them claim to be very busy. My friend Brent Veitch from Rock Paper Sun is booked up well into the new year.
• A number of booths were offering Photovoltaic options. Prices still are very high for this technology. One provider had an offer for a 2.6KW on gird system for about $26000.
• Affinity Credit Union had a large booth promoting special financing for green residential construction projects. They did not have a lot of detail but advised that I contact one of their many branches.
• SaskPower/SaskEnergy had a booth promoting their loans. Of special interest was a low interest loan of up to $50000 for renewable energy systems such as wind, solar or geothermal.
• WSE Technologies was showing some of their new product lines. They are carrying a number of new products that are worth considering. I am meeting with them in the next few weeks to get a better understanding of their products and services
• At least two Integrated Concrete Form manufacturers were represented. One promised to send me more information on their product. I will be doing a blog on ICFs in the near future
• Rick Olmstead, the inventor of heat exchange ventilation systems had a booth. You may also know Rick as one of the principals in the Rivergreen Ecovillage project.

Sometimes it is interesting to note who was not there:

• Window technology is a very important part of any passive solar strategy. There was no one there from the window manufacturers
• Structured Insulated Panels (SIPs) are being positioned as a green building alternative. No SIPs manufacturers were represented

I really enjoyed the time I was able to spend at the conference. Next year I plan to be there for the full day.

On October 15, I had the opportunity to attend a green roof workshop at the center in Vancouver. The workshop was led by Jonathan Hays, the technology transfer coordinator for the Center.

There are two types of green roof designs:

• extensive green  roofs use a vegetation layer between 2 to 6 inches deep. This shallow planting medium reduces costs but restricts the type of vegetation that can be planted.
• Intensive green roofs have a much thicker vegetation layer. This design is much costlier but allows for unique designs and public access.

Construction techniques have been well tested through experience in Europe. The diagram above [taken from CMHC’s “Green Roofs -  a Resource Manual for Municipal Policy Makers”] shows  the multiple layers required for the proper construction of a green roof.

The Center  at BCIT  has an extensive green roof with one third of the roof using a 3 inch  vegetation layer, one third using a six-inch vegetation layer and the remaining one third left open as a control area.  The center also tests a number of other roof types in several roof emulation modules [REM].

My conclusion after visiting the center is that green roof  technology should be considered for any flat roof commercial buildings but that is not yet ready for residential use in Canada.

For more information on green roofs, check out www.BCIT.ca/greenroof

Dr. Dumont is from Saskatoon and has spent most of his career studying energy efficient home construction. We are planning to build a net zero demonstration home at Sarilia Country Estates (www.sarilia.com) and we are very fortunate to have Dr. Dumont on the design team.

figure 1: from presentation by Gorden Howell on the Riverdale NetZero home

In his January, 2003 article in SOLPlan Review, Dr. Dumont outlines the integrated design process:

1) Define the design goals – every owner has different goals for their home. It is important that everyone on the design team understands these goals.

2) Be quantitative with goals where quantitative criteria are appropriate – goals should be quantified in a number of areas:

• • energy related goals
  • air quality related goals
  • water conservation goals
  • natural lighting goals
  • recycling and solid waste management goals

3) Proceed with integrated design

The integrated design session for the Lepage NetZero Home is planned for Monday October 5. Our preliminary design objectives follow:

Figure 2: from Lepage NetZero Home – Planning phase

We are very excited about our NetZero Home and the opportunity to work with Dr Dumont. More to follow …