Category Archives: Home Retrofit

Follow Up Thought for Friday’s Summer Cooling Tips.

DeeDee and I started outside. The info from the back deck did not make the cut and I let it slide when i did the blog summary of her story.  So …

Shade Works

This is an Infrared image on one of my first new homes.  The 2 foot cantilever bay clearly shows the effect of the shade. There is a 20° F difference in the temperature between shaded and unshaded areas of the wall. The high temperatures on the side of the house are in the area of 128° F.  It is 97° F when I took this one.

Shade works.  Building a new home with a south facing set of large windows. It is worth your money to have a deck with a roof, or pergola over it. If you have an existing home, the Pergola is a great idea.

Concepts like this have been recommending in my Home Energy Audits.

This simple table will keep your home cool

Table 1 Jean-Sébastien Lagrange and Raphaël Ménard with their Zero Energy Furniture Climatic Table.

Consisting simply of a surface and legs, the table is one piece of furniture that has remained largely the same for thousands of years. But now, a French design duo has come up with a way to turn the humble table into a means of climate control that doesn’t use any electricity. Paris-based industrial designer Jean-Sébastien Lagrange teamed up with French engineer Raphaël Ménard to create the Zero Energy Furniture table, also known as the ZEF Climatic Table. The ZEF table looks like any other with a sleek design of a solid plank oak top and angled legs — but it could hold the secret to cutting energy costs by as much as 60%.

 

Table 2A close up of the ZEF table, which could cut energy needs by as much as 60%.

 

“We wanted to see if it was possible to address climate and energy issues on a furniture scale,” Lagrange told WIRED.

Beneath the oak table are a series of phase-changing materials (PCMs) placed between the wood and anodized aluminium bottom. The materials soften when the surrounding room reaches around 71 degrees, absorbing the excess heat, and then harden once the temperature dips back below 71 degrees, releasing the trapped heat with the help of the aluminium and causing a noticeable change in the room’s temperature.

Table SpongeThat means the table is essentially working like a “thermal sponge,” as Lagrange and Ménard put it, sucking up excess heat and then releasing it once the room becomes cool enough.

According to the inventors, the table has the potential to reduce heating needs by as much as 60% and cooling demands by as much as 30%, which could save a lot of money as well as energy.

It’s a feat of engineering that makes the most sense in homes that don’t have climate control.

In climates where the temperature can drastically swing from hot to cold in short spans of time, the ZEF Climatic Table is most useful. For example, if a room heats up on a sunny day and then the temperature drops at night, the ZEF table would make the climate in that room more consistent.

The ZEF table works best in rooms that undergo significant temperature changes frequently.

The Full Article on Business Insider Australia


 

This article is reprinted in part from the above digital source. It was originally from Wired and was brought to my attention by ASHRAE. Phase Change Materials have many applications in heating and cooling. One phase change material everyone uses is water.  At 32°F it changes from solid to liquid or liquid to solid. Of interest to energy efficiency are materials that act in this way around 70°F.

A Healthy Home Part 4 – Free of Combustion By-Products

This post is written as a conversation between a homeowner and myself as it could have occurred during a Home Energy Audit. It is actually the gathering together of several conversations on different audits over the past few years.

smoky fires

 

A Healthy Home is Free of Combustion By-Products

Homeowner: Oh!  You mean no Carbon Monoxide!  I have a  Carbon Monoxide Detector.  It has had some false alarms, but it has never found a problem.

The Energy Guy: OK!  Carbon Monoxide (CO) is one by product of combustion.  There are others.

Homeowner:   So, you mean the house must be all electric?

The Energy Guy: No, not necessarily.  An all electric home, might have a fire place, and an attached garage. Both are sources of CO and other byproducts of combustion. A healthy home will deal with all of these in some fashion.

Homeowner: What other things are you talking about besides CO?

rustDHWThe Energy Guy: The one I see the most of is moisture.  Many of the flue pipes I’ve seen have rusted from the moisture.  If you have a gas hot water heater, look at the top.  Is the top rusting, what about the flue pipe or the draft diverter? Moisture from open combustion appliances also increases the humidity in the home and adds unneeded work to your air conditioning unit, increasing the bill.

There are others, such as Nitrogen  Dioxide, and Sulphur Dioxide, and various particles of all sorts.

Homeowner:  So, those are like Carbon Dioxide?  Something that is just there?

The Energy Guy:  Yes!  They are just there, with two concerns.  First the Lung Association points out the health effects of Sulphur Dioxide include:

  • Wheezing, shortness of breath and chest tightness and other problems, especially during exercise or physical activity.
  • Continued exposure at high levels increases respiratory symptoms and reduces the ability of the lungs to function.
  • Short exposures to peak levels of SO2 in the air can make it difficult for people with asthma to breathe when they are active outdoors.

Health effects of Nitrogen dioxide include:

  • Increased inflammation of the airways
  • Worsened cough and wheezing
  • Reduced lung function
  • Increased asthma attacks
  • Greater likelihood of emergency department and hospital admissions
  • Increased susceptibility to respiratory infection, such as influenza

Homeowner: I’m pretty healthy, but you said ‘First!’

The Energy Guy:  The second is moisture. Moisture could be a high humidity situation, or moisture from the combustion that produced these dioxides and if you inhale some of them, or moisture in your nose and lungs. Here are the basic chemical equations for those interested.

Sulphur Dioxide plus Water ends up as Sulphuric Acid [SO2 + H20 ===> H2SO3 (sulphurous acid) SO3 + H20 ===> H2SO4 (sulphuric acid)]

acid_storageNitrogen Dioxide plus Water ends up as Nitric Acid [NO2 + H2O ===> HNO3 + NO]

Homeowner: But acid eats things up!

The Energy Guy:  Yes, it does. These acids start the rust process, I mentioned earlier. The other place you can look for rust is to look at the flue on the roof of some homes. If the coating is attacked by the acids, then rust occurs.

So How do I keep this stuff out of my home and away from my family?

co detectorThe Energy Guy:  First install some Carbon Monoxide Detectors.  If your furnace and water heater are in the basement, you need one down there.  You also need one near bedrooms.

Homeowner: OK!  I’ll get that one that works with my Nest!

The Energy Guy:  That will work for one.   The Nest Protect is like most CO detectors, it will alarm at the higher amounts of CO as required by the Underwriters Laboratory requirements.   These start at 70ppm of CO for an hour. Professional organizations such as ASHRAE and NIOSH list 35ppm as the level for technicians and others to stop work, turn off equipment and evacuate the building. A low level detector is important.

Low Level CO detectors do not meet the UL requirement because they alarm at lower levels, typically 20ppm.    15-20ppm CO levels have been found to impair judgement in people exposed for short periods of time.  The UL testing does not allow a CO detector to pass if it alarms below 30 ppm. Low level CO exposure can result in headaches and general malaise.  If you are exposed to low levels over a period of months or years the effect is unknown at this time.

Homeowner:  OK!  So I’ll get a low level detector also.  What else can I do.

The Energy Guy:  Do some careful air sealing between the garage and the house. You can add exhaust ventilation to your garage as recommended in the International Residential Code. Open the door before you start the car, and then immediately back out. More information about CO and the garage. Air sealing here and a simple closer on the door to the garage will help keep CO and other pollutants from the garage out of the house.

Inside the house, you can buy smart when you replace your water heater or furnace.  Buy sealed combustion units.  These are generally more efficient units, so they will save you some on your bill each month.

95Water Heaters can be sealed combustion, such as the demand models or a power vented unit. Either of these units can be identified with the use of PVC exhaust flue, instead of the metal flue needed by traditional units. They do not need the metal, because the exhaust is a lower temperature. This has a side effect of increased efficiency. The image to the right is the flue of at sealed combustion furnace.

Finally, think about your wood burning fireplace or your gas oven.  These also create the same problems.  Here a low level CO detector would be very valuable. Following the fireplace manufacturers instructions in keeping the glass door shut and having it checked regularly are important.  For a gas range, especially with a gas oven, install an exhaust fan that vents to the outside.

 

Some of this information came from the Maine Indoor Air Quality Council

Some of this information came from the American Lung Association

A Healthy Home — The first of this series

A Healthy Home Part 3 — Well Ventilated

Fresh AirA Healthy Home is well ventilated.  Everyone knows fresh air is important. This should be easy.  Well ventilated in more than just bringing in fresh air. The concepts are certainly easy, the details on the other hand take some thought and planning.  A new home ventilation strategy is fairly straight forward to design and implement. An existing home needs the input from the occupants and good analysis to address the problems. An effective ventilation strategy should address these issues in either new or existing homes.

  • Remove humidity, odors,, or significant problems from specific areas.
  • Remove stale, musty or other objectionable air.
  • Allow the occupants to choose fresh air sources that can be filtered or treated in other ways
  • Allow the occupants to choose to open windows when outside weather is appropriate
  • Allow the occupants to operate a system that can provide the amount of fresh air, to the appropriate places, in adequate amounts when needed
  • Provide fresh air when the outside air creates potential problems, such as Ragweed season or when other allergens are active
  • Provide air movement within the home, without the use of the expensive blower on the furnace or heat pump.
  • Allow minimal use of heating or cooling equipment during the shoulder seasons, when temperature changes are minimal, while keeping the home comfortable.

Billings QuoteHow much fresh air is needed?  Going back to the 1890’s, the number has been pegged at 30 CFM (cubic feet per minute) per person. This number was validated in a number of different studies and with the public health authorities in larger cities, dealing with large apartment buildings and recurring respiratory diseases.  I was pointed to the quote at the left by Allison Bailles. he located the original book on Google Books, page 20.

Beginning in the 1930s, research into changes in building techniques began to show the optimal number was closer to 15 CFM per person.  Some of the changes in construction included the increased use of forced air heating, moving from balloon framing to platform framing, increasing square footage, and the use of insulation in walls and attics. The formula changes from time to time and everyone has an opinion on details. The common point remains, fresh air is needed in every house.

Part of the Ventilation is removing air with a problem. Where is that?  Humidity is found in rooms that use hot water and basements.  Showers, tubs and cooking are the large sources of humidity.  The smells from food preparation and cooking can be very mouthwatering.  When the meal is finished and the refrigerator is full, the lingering smells become odors.  The answer is some spot ventilation in these areas. If your basement has a humidity problem, you can tackle that with a fitted sump pump cover to contain the humidity, and work to eliminate any water seepage.

vent fanSpot ventilation is a window that opens and an exhaust fan. The size of these fans is part of the formula that is specific to each home. The features of the fan are common to all homes.  It must be quiet. Builder grade fans are noisy. Noise in fans is measured in ‘Sones’. The Sone is a linear measurement of noise, compared to the decibels used by OSHA and others which is an exponential measurement.  Linear is better for quiet sounds, and decibels is better for loud noises. Fans should be less than 3 sones, and preferably less than 1 sone.  Reasonably priced fans are available that rate a 0.3 sones. A 1 sone fan is very quiet.

UnknownFans are certified for air flow and noise levels by the Home Ventilation Institute. HVI certification is very common and includes both the Sone rating and CFM rating.  When installing a fan, you must consider the duct losses that will occur in meeting the required air flow.   The rates for bathroom air flow  are 50 CFM, and 100 CFM for a kitchen.  Do not expect to buy a 50 CFM fan for a bathroom and connect it to 6 or 8 feet of duct work, and obtain 50 CFM.  I have measured 30 CFM routinely in these set ups.

Most people understand that various parts of their body are just a part of the whole.  If you start some type of therapy, there may be a side effect. Physical Therapy starts and you end up with some sore muscles, aha!  Side Effect!  Start a therapy for cancer and your hair may fall out, aha! Side Effect!  Your home works the same way.  Each part is just part of the whole. Change something, aha! What is the side effect?

House-System-imgAll of the items in the list above are part of the whole. For an existing home, some specifics of that house may indicate concentration on one or another of those areas.  A home built in the 1920’s will benefit from a different approach then a house built in the 1980’s.

A new home should have the ventilation system that meets the general points above.  The natural ventilation provided when windows and doors are opened, or the mechanical ventilation system that allows filtered and perhaps treated fresh air brought in from specific places and in specific amounts, allow the occupants to make the system work as they need.

 

This post is part of a Series on A Healthy Home

 

 

A Healthy Home

Healthy HomeBuilding a new home, gives the homebuyer an opportunity to build in all the things they want. The floor plan, bedroom arrangement, windows are all important.

Also right up there is a house that is healthy. Everywhere you look, someone is pitching, this is healthy for you.  We have lots of buzz words for healthy.  Organic, whole grain, anti-oxidant, reduced fat, low sugar, wellness, all-natural are but a few. How do you make a house into a healthy home?  It starts with design and a few simple objectives.   Ideally, a healthy home is:

  • Dry
  • Clean
  • Well Ventilated
  • Combustion by-product free
  • Pest Free
  • Chemical Care
  • Comfortable
  • Safe

read beforeIt seems fairly simple.  We want a roof over our head to keep the elements out.  Hot or cold, rain or snow, we don’t want them in our home.  The dry home starts with a well constructed roof.  That keeps the weather related water like rain or snow out. Then the walls, and the foundation.

Clean may be obvious, or not. Well Ventilated and Combustion by-product free, along with pest free, no toxic chemicals, comfortable and safe seem also to be obvious.  There is a saying about the Devil being in the details.  It is certainly that way in building a home. So a few details on these topics that make up a Healthy Home are important.

I will be posting a series based on the Healthy Home. We will take a look at each of the points listed above and what they mean to the home owner.

Part Ia   How Dry is Dry       Bulk Water from Precipitation

Part 1b  How Dry is Dry       Bulk Water From other Sources

Part 1c  How Dry is Dry       Water Vapor

Part II    The Home Starts Out Clean

Part 3    Well Ventilated

Part 4     Free of Combustion Byproducts

Part 5     Pest Free

Part 6     Chemical Care

Using One HVAC System for Two Areas

My first audit was triggered by the homeowner concerned that the upstairs was several degrees warmer than downstairs. Since we all have experienced Hot Air  goes up, it makes some sense.  In this case the difference was 15° F at 8:00 am, rising to 20° F by noon that August morning.  Yes, it was hot.

4 square craftsmanThere are a number of ways to help this out, for existing homes. Which one is best depends on the specific home, the existing setup and the homeowner.  For new homes, it usually falls to the HVAC guys to work out.

In a new 2 story home, it is common to see two HVAC units.  One in the basement for most of the home and one in the attic for the second floor.  Some builders, concerned with cost, or space considerations, will try a Zoned System.  You can also find Zoned Systems in single story homes, with the master suite on one zone and the rest of the home on another zone.

furnace bypass zoneTypically, the set up uses a bypass and several dampers to control the air.  The wisdom of this approach is that changing the air flow through the unit costs a lot of $$$$.

In the video below, John Proctor, goes through the measurements and calculations of using or not using a bypass and dampers to figure out exactly what is happening.  His conclusion:  The Bypass Damper set up costs 22% – 32% more.

This video is primarily written for HVAC contractors and others interested in the details and workings of air conditioning.  If all the numbers make your eyes glaze over, that is OK.  All you want is comfort, a Bypass dampened system may do that at a cost. It may have the cost and not do that.  So if you are considering a Zoned HVAC system,  tell your contractor —  ‘No Bypass Dampers’!  And refer them to this post.

Some Results from Energy Improvements

When doing a Home Energy Audit, I always tell people that what I find is not good or bad. I tell them that what I can recommend for improvement depends on  the cost of their Utility Bills.

If you have a water leak, we all know that paying the price to a plumber to fix it, will cost us when the plumber comes. We also know if we don’t fix it, we can pay the water company that amount over 1 or 2 or 6 months. How long depends on the amount of the leak and the cost from the Utility for your water. And then we still have to pay the plumber. so we make a choice.

Blowing insulation into the walls!

Blowing insulation into the walls!

Wendy stuffing insulation into the hopper!

Wendy stuffing insulation into the hopper!

Some choices are easy, for improving the efficiency of a home.  Most homes with a tank type hot water heater inside the home, in a balanced or cooling climate (south of the Kansas / Oklahoma border) will benefit from installing a water heater insulating blanket.  They cost about $25.00 and typical savings just north of the above line can run from 6 – 8 dollars per year. So at $6 bucks a year, the blanket pays for itself in about 4 years. And most people can afford $25.00.

Other choices are somewhat tougher.  Instead of $25.00 to invest in the improvement, cost can run $2,000 to insulate a basement.  If you spend time down there, you know it is a little colder in both the winter (brrr) and the summer (nice), then upstairs.  Again, using some Wichita area numbers a homeowner could save in the area of $350 per year. Each house is different, so I am using some averages from various audits. If you apply this  savings over 6 years, the insulation is paid for and you still save the money. The hitch? It is harder to come up with $2,000 instead of $25.00.

In 2011, I had an Energy Efficiency Project approved under the Efficiency Kansas Program. They loaned some cost, I paid some costs and we added some (a bunch) of insulation, air sealing to cut the infiltration, replaced a 18 year old furnace and air conditioner. I also added an Energy Recovery Ventilator.

Wade in the attic! Fixing a dropped soffit in the kitchen! You can see the 3:12 pitch on my roof.

Wade in the attic! Fixing a dropped soffit in the kitchen! You can see the 3:12 pitch on my roof.

My payment over the 15 year loan is 870 per year, due monthly on my Utility Bill.  So the question is, how did I do with saving some money?  I have been tracking my Natural Gas and Electric billings, with numbers going back to 2009. When I changed HVAC systems, I went to an electric Heat Pump with a gas furnace for back up or emergency heat. As a result, my gas bill dropped and the electric bill, which includes the loan repayment amount is higher than I can remember.

To account for the change, I had to do something with the natural gas, billed in MCF (1,000 cubic feet) and the electricity, billed in KWH (kilowatt-hours).  I decided to convert the gas usage to KWH for ease in comparing before and after.  I also wanted to be able to compare usage against the weather.  Some summers are hotter than others and some winters are warmer then others.

The National Weather Service tracks our weather very well.  You can get an F-6 Report from most airports around the country. In Wichita, we have a choice of 3.  There is Mid-Continent, the primary commercial airport; there is Jabara Airport, a smaller facility that specializes in private airplanes.  And we have McConnell AFB.  All have weather observations and reporting.

The F6 NOAA Report for March, 2011 at ICT. The 2 columns between the red lines show the HDD and CDD.

The F6 NOAA Report for March, 2011 at ICT. The 2 columns between the red lines show the HDD and CDD.

How did I compare the before and after?   Excel works great for prototyping number crunching and charting the results.  I collected my data on usage, cost and Degree Days from the Weather Service.  I built two charts. First one covering January 2009 through present. After looking at this chart, I built another showing January 2011 through present.

The charts show three (3) lines. The Blue Line represents Heating Intensity by month.  I took Heating Degree days, multiplying by 5.  The Red Line represents Cooling Intensity by month. I took Cooling Degree days, multiplying by 3.5.  The Green line represents Energy, show in KWH.  I converted my gas usage to KWH by ” MCF x 293 “. Then I added the KWH from Electric and Gas to chart the Green Line.4 years

2009              2010                     2011                  2012                 2013

If you look at the top peaks of the Blue Line – you see the cold months. Imagine a level line averaging those tops. Somewhere between 4000 and 5000 on the Y-Axis. Look at the Red Line Peaks – you see the hot months. Imagine a level line on the Average of those peaks, just a little over the 2000 on the Y-Axis.

Now look at the Green Line, it goes up in the winter, and summer, down in the spring and the fall. This line doesn’t really run level on the peaks. If you pick about 6500 on the Y Axis in 2009 and 2500 in 2013, the line slopes down.  The Red vertical line shows when the improvements were made. This chart shows 3 years prior to the date of improvements and 1 year after.

The Chart below just shows one year before and 1 year after.  So the horizontal spreads out a little. I think the point is made in either chart.  The improvements require less energy to be purchased.

How much less in dollars, instead of Energy Usage? I’m saving my 870 annual repayment amount plus enough to repay myself over 15 years for what I kicked in.  And a little extra.

2 years

2011                                    2012                                   2013

Some one will ask why did I adjust the HDD and CDD numbers.  I did it to match the scales on the charts.  I first set it up with direct numbers. When you looked at the chart you could not make out any significant ups or downs to compare. So I reworked the numbers with multipliers, to make the charted numbers line up better.

In September, 2011 the chart shows 155 HDD, 591 CDD, the energy usage in KWH is 2261.  In September, 2012 the chart shows 0 HDD, 960 CDD with 1217 KWH used. Using the same Y-axis scale required some changes. So I used a multiplier to move from direct Degree Days for Heating and Cooling to an intensity measure for heating and cooling.

Thanks for following along.  I will make another post with more of this story.

Build Your Own Home Energy Audit

A comprehensive Home Energy Audit takes time and covers a number of areas. It provides lots of information and recommendations.  A homeowner may choose to limit the inspection to those items of their concern.

The energy efficiency of each home combines an analysis of the components of the home and how well they are installed.  Think of a bucket of water, the bucket is the walls and ceiling of your home. A pinhole in the bucket will drain the water from the bucket and the heat from your home!

A Home Energy Audit looks at the ability of each building component to resist the transfer of heat. The air tightness of each component is also reviewed.

This post covers a description of each part of a comprehensive Home Energy Audit.

Pricing, previously contained in this post, is posted separately.

Utility Analysis

The actual usage over the last 12 months of Electric and Gas is compared to the home size and evaluated. This requires information from the Utility Companies.

Infiltration Testing                 

(Multi-point Blower Door Testing with Thermal Imaging and Indoor Air Quality Analysis)

Everyone has felt a cold draft at one time or another. Since the air blew in and the house didn’t pop like an overfilled balloon, the air blew out somewhere else.  This test simulates a 20 MPH wind on all four sides of the home at the same time. It allows an actual measurement of leakage and it identifies the leaks. This allows a specific plan for the leaks in your home to be fixed.

The recommendations will include effective measures to improve indoor air quality, not just install what the salesman has in-stock. If you have de-humidifiers running this Testing is important.

Ceiling Evaluation:

The ceiling and attic areas are examined for insulation, ventilation and thermal bypasses. This is done from the outside of the home, the inside in all rooms and from the attic. It may involve remote camera usage. If Infiltration Testing is part of the package, information from the Thermal Imaging portions are applied to the ceiling Evaluation.

Foundation Wall Evaluation (below grade):        

In most homes a major source of heat loss is from the crawl space, the slab or the basement walls. There are generically referred to as the foundation of your home. Traditionally, builders have confused the thermodynamic principles involved, with hot air rising and heat loss, to falsely assume that basements cannot be kept warm.

Wall Evaluation (above grade):

Homes over twenty years old, or homes with a major insulation failure may benefit from a specific wall evaluation for walls above grade.  It is part of a comprehensive  energy audit. All wall evaluations are conducted with Non-Destructive-Test Methods to start. Depending on the home, the type of construction, access to various areas, further testing that involves minor holes being drilled will be discussed with and approved by the homeowner before the end of the evaluation.

The condition and energy efficiency of your exterior siding is done at this point.            

Equipment (furn. AC, hot water):                    (Includes safety checks on Gas Fired Equipment)

Your heating and cooling equipment is a large investment. What are the efficiency ratings on your existing equipment and what is available on the market? How does a home owner sort out fact from sales pitch.  This inspection includes safety testing for gas fired equipment. Furnace, Heat Pump, AC, Hybrid Heat Pump, are included.

Windows and Door Evaluation:           

Windows are advertised everywhere.  On the Radio, TV, the newspapers and other print media all carry large volumes of sales pitch for replacement windows. The FTC has fined some window companies for outlandish claims on energy savings.

Are your windows an energy problem? Can those energy problems be fixed or should the windows be replaced? What is the best for my home?  Low E, argon filled, double pane, triple pane? How does a double pane window save energy?  All these questions and more are answered. And you get the answers from someone that does not have a financial interest in your purchase or non-purchase of a product.

Windows and Doors are both holes in the wall.  From an energy loss standpoint there is not much difference. Doors are not as heavily advertised, but they are pushed after the salesman gets to quote your home.          

Computer Modeling and Reporting

The Comprehensive Home Energy Audit provides a complete energy usage model and reporting of problems, recommendations and solutions. Interactions between building components are considered in the computer model. You can go from the report to soliciting firm prices from a contractor or doing it yourself with this report. This reporting will qualify for applying for and Energy Improvement Mortgage if you are buying a home, or refinancing your current home.

If you choose various parts of the Home Energy Audit, written reports and recommendations will also be provided. These will all you can go from the report to soliciting firm prices from a contractor or doing it yourself with this report. The reports are limited to the selections made. Interactions between building components are not considered.

Duct Leakage Testing Not included in the comprehensive audit.

Some comfort and energy loss issues involve improperly installed ductwork. Testing is easy. Fixing these problems can vary in complexity depending on the home.      

Lighting and Appliances Not included in the comprehensive audit.

Incandescent, halogen, CFLs, LEDs, which is best for your home?  Not every fixture needs a high efficiency light! Should I get a new fridge or other appliance?  All these are part of the Lights and Appliances.

Bonus Room (over the garage, or in the attic) Included in the comprehensive audit.

Rooms placed over a garage or in the attic are a special case. They are part of a comprehensive audit. They can be an individual item, with infiltration testing, due to the unique construction problems with them.

For more information or to schedule a Home Energy Audit:  

V / T  316 641-5258  or  email:  info@efficientenergysavers.com

You have an Energy Star New Home – How accurate are the Projections?

This study is of interest to all HVAC, Insulation Contractors. It is also important to Home Owners.  An Energy Audit makes recommendations and projects cost effectiveness based on a computer model of the Energy Use in each specific home.

How much can you count on those projections? Home Energy Usage depends on three things!

  • First:  The Weather!
  • Second: The Lifestyle of the Family in the Home!
  • Third: The construction of the Home!

Mother Nature has control of the weather! Lifestyle is the difference between having 3 High School Football Players in the family, or 3 High School Cheerleaders.  Energy use will be different. Then what happens to the use when those kids go off to college.

This study actually compares the projections from several hundreds of thousands of homes to their actual usage.  You can read the RESNET Summary. You can read the report itself. I have reprinted the Summary with the link to the Report below.

The original Summary can be read here.

My conclusions:

  • The correlation from projected usage to measured usage over time justifies the reliance on computer modeling using the software to guide your decisions on prioritizing improvements in energy efficiency to your existing home.
  • The correlation of projections for Energy Star New Homes to actual usage gives Builders, Contractors and Home Buyers the confidence to use an Energy Star New Home Certification for lowering the ongoing Operating Costs for Energy in a New Home Purchase.

John Nicholas

 

PROJECTIONS FROM HERS ACCURATE August 22nd, 2012

Posted by RESNET under RESNET News

Over the years, there have been discussions over how accurate are home energy ratings in predicting the energy use of rated homes. To enhance the discussion of the accuracy of home energy ratings’ energy use projections it would be good to review a study conducted and published by Advanced Energy on a large set of homes in Houston, Texas. The authors of the study were Michael Blasnik of M. Blasnik & Associates and Shaun Hassel and Benjamin Hannas of Advanced Energy. The objective of the U.S. Environmental Protection Agency supported “Houston Energy Efficiency Study” was to assess the actual energy use of groups of homes built to different energy efficiency specifications in Metropolitan Houston – typical non-program (baseline) homes, ENERGY STAR® homes labeled by a Home Energy Rating and guaranteed performance homes.

More than 226,000 homes built from 2002 through 2007 by dozens of different production builders were included in this study. The large dataset also provided the opportunity to analyze how certain construction characteristics are related to actual energy usage. Data collected for this project included billing data for all new homes built in the CenterPoint utility service territory from 2002 through 2007, information from property assessor databases of four counties, detailed building characteristics for tens of thousands of ENERGY STAR homes from CenterPoint’s ENERGY STAR Homes tracking database, and detailed data files from energy raters including the home energy rating software tool, REM/Rate, input files and building shell and duct leakage test data. The study did not involve any direct data collection in the field but instead relied upon existing data sources.

This approach allowed the scope of the study to be much larger in terms of the number of homes analyzed but left some gaps in our understanding of some details, especially of baseline homes. The overall dataset includes hundreds of variables for 226,873 homes, including 114,035 potential baseline homes, 106,197 ENERGY STAR homes and 6,641 guaranteed performance homes.

Although consumption differences across groups of homes are smaller than advertised, ENERGY STAR homes perform very close to the predictions of the models on average, while baseline homes perform better than the reference homes defined by the HERS standard. ENERGY STAR uses a base case reference home defined as minimum local code specifications combined with the least efficient cooling, heating and hot water systems available, a leaky building envelope and a poor duct system. Using this yardstick to measure the performance of the ENERGY STAR houses in the study, they did quite well – showing a strong and fairly consistent relationship between actual and projected performance for both heating and cooling. Therefore the apparent lack of savings is attributable not to underperformance by the ENERGY STAR homes but to the fact that the baseline houses in Houston perform considerably better than the ENERGY STAR reference house.

The relationship between REM/Rate cooling load projections and actual electric usage was examined graphically and statistically for 10,258 homes with sufficient data. REM/Rate projected an average cooling load of 5,506 kWh/yr while the billing analysis estimated average cooling loads at 5,677 kWh/yr, about 3 percent higher – excellent overall agreement. Although the analysis found no systematic bias in the REM/rate cooling projections, there was a large amount of variability in the data. Findings revealed that the correlation was higher between house size and cooling load than between REM/Rate projected cooling load and actual usage. However, the study team feels confident in stating that when using current modeling software with energy-efficient new homes, there is a strong and fairly consistent relationship between actual and projected performance using REM/Rate for both heating and cooling. REM/Rate also estimated the average heating usage of program homes fairly well – only 4 percent lower than the measured loads.

To download the study click on Houston Energy Efficiency Study

Ductless Mini Split Heating and Cooling – Is it any good?

I’ve had the concept of a Ductless Mini Split HVAC unit brought up recently. I’m out doing a home energy audit, I’ve been asked on Twitter and in other contexts several times.  A discussion on a Professional Linked In group and my follow up comment has resulted in this post.

First – What is a Ductless Mini-Split?  The simple answer is ‘One type of residential HVAC equipment’.  Other common types of residential equipment are Single Package Unit and a Split Package System. An example of a Mini Split on the right by LG Electronics USA Commercial Air Conditioning. The top image is what you see inside. The bottom two views are of the outside unit. LG is one of many mini-split manufacturers.

If you are building to Energy Star, your HVAC contractor must perform various calculations to figure the size of the units, set up the duct work and select the unit. These calculations are specified by the Air Conditioning Contractors of America (ACCA) an industry trade group. Known as Manuals J (size) D (ducts) N (equipment selection).

If the process and calculations, especially Manual N will show a Ductless Mini Split as fitting the need, great! An example of a Single Package Unit on the right. Outside both summer and winter.

If you are not building the Energy Star – the 2012 recommended Energy Code requires the same process.

If your jurisdiction has not adopted the 2009 or 2012 Energy Code, the prior Residential Mechanical Codes require ACCA calculations or similar. The outside condenser of a Split System on the Left.

Heating and Cooling equipment is routinely oversized in existing homes and in new construction. This approach avoids the math and fits the American image of ‘bigger is better’. It also avoids after hours service calls concerned with the home not heating up or cooling down fast enough.

HVAC equipment, just like your car, operate most efficiently traveling at a constant speed. For your car a highway speed without starting or stopping in city traffic is the efficient speed. Note the Fuel Economy Numbers show the best and the worst MPG figures for each model. At the right is an example of the inside unit of a split system.

Due to the variations in climate from South, with little heating and lots of AC; to the North with a lot of heating and no AC; ACCA uses a design temperature in the calculations. Essentially you can figure the design temperature for your area. The National Weather Service publishes the daily highs, lows and average temperatures for each weather station. The report you want is monthly and is referred to as a J6.

How to figure that is a little much for this post.

A properly designed HVAC unit, like your car will run constantly at or in excess of the design temperature. So these hot summer days, most of us are above the design summer temperature; your AC is OK if it runs all the time. Preventive Maintenance is needed for the HVAC equipment, not sleep.

All that aside; a ductless mini-split is a great choice for a smaller space. My experience with specifying these for Homeowners is that HVAC manufacturers and contractors dearly love them. They are priced accordingly. At the left, the outside duct of a Single Package Unit, typically with no insulation.

 

The Mini Split gets away from the use of ductwork to distribute the conditioned air. That is the strength. Most ductwork in our homes is not designed correctly, it leaks and requires too much fan capacity to distribute the conditioned air. In the right sized space, going without ducts has many advantages.