Category Archives: Energy Efficiency News

Why The Way your AC is installed Matters! Part I

Screen Shot 2016-06-24 at 8.49.56 AMThe Air Conditioning Contractors of America (ACCA) publishes ANSI Standards for HVAC Contractors to follow. These professional standards are well known in the Home Performance Industry and the HVAC Contractors.  I found a link on their website this morning to a study showing the problems caused with problems that can easily occur if the Industry Professional Standards are not followed.

I covered a study from California about these types of faults recently. This one was completed by NIST.  The National Institute of Standards and Technology, a part of the US Department of Commerce.

CookA quick review of the reports shows many technical details and mathematical formulae.  That forms the back ground for comparisons with other studies.  However, they did write in some plain English for the rest of us. Here is one of their findings, about the performance of heat pumps.

A Heat Pump provides both heat and air conditioning. It is efficient because it moves heat.  In the summer, it moves heat from inside to outside, just like an ac unit.  The same technology and principals. In the winter they move heat from outside to inside. Yes, there is heat outside at cold temperatures.

Think about your refrigerator. When it gets up to around 40° F inside, the unit turns on and finds the heat in that 40° temperature and moves it out of the refrigerator to keep your food cool and fresh. If you watch your temperatures outside, you know more heating is done at 40° and above than at 20°.

This findings for a heat pump cooling your home apply to geothermal heat pumps, regular heat pumps and to air conditioners. They are all working on the same principals.

The first fault they report on is having the wrong size unit.

Changing the size of the heat pump for a given house – either undersizing or oversizing – impacts the heat pump performance in several ways:

  • Cycling losses increase as the unit gets larger; the unit runs for shorter periods and the degraded performance at startup has more impact (parameters used in simulations are: time constant = 45 seconds, or CD ~ 0.15).
  • In the cooling mode, the shorter run periods impact the moisture removal capability (i.e., ability to control indoor humidity levels) because operational steady-state conditions are an even smaller portion of the runtime fraction.
  • In the cooling mode, continuous fan operation with compressor cycling greatly increases moisture evaporation from the cooling coil. However, this impact is minimal with auto fan control (indoor fan time ‘on’ and ‘off’ the same as that of the compressor), since only a small amount of evaporation occurs with the assumed 4 % airflow during the off-cycle with the indoor fan off. If the air conditioner controls include an off-cycle fan delay – that keeps the fan on for 30-90 seconds after the compressor stops – then the impact of off-cycle evaporation is in between these two extremes (Shirey et al., 2006). The results in this study assumed auto fan operation with no fan delay.
  • Heat pump sizing also affects the level of duct losses.

A improperly sized unit will run for shorter periods, and will turn on and off more often. That is just like driving your car around downtown Wichita. Lots of stop lights. Compare you gas mileage to highway driving at a steady speed of 55 mph or higher.

OK, I know efficiency isn’t as important as being comfortable. So the next item is the comfort side.  Running you AC like your car in Down Town, doesn’t remove the humidity as well. Your house temperature is cool, but the humidity is high and you turn down the thermostat again to get rid of the humidity. Pretty soon you are cold, and yet you are not comfortable because you feel the high humidity.  Then you go out and buy a de-humidifier.

The third item is also a comfort issue. That is the advice of many HVAC technicians to set your AC fan to run continuously. When the AC shuts off and the fan keeps running, the humidity the AC just removed from your house is put back in. Oops!

DadBabyESFinally the report mentions duct losses. They are important in a home that has no basement. In those homes ducts can be located in the attic or the crawl space, or both. If you have one of those houses, I would be glad to address that one in the comments. So leave a comment if your are interested.

How do you get a right sized AC unit?   Your HVAC contractor can run a series of calculation found in the professional standard from ACCA Manual J.  It is a Load Calculation.  For cooling it considers the insulation in your home, the windows and size of the home and other details. It can be done on a paper worksheet or a spreadsheet. Both are free from ACCA. Most contractors have a software program to run these Load Calculations.

Load calculations for cooling, are a balancing act. The homeowner wants a home that is cool in the summer and in Wichita, they want the humidity controlled.  Without a lot of formulae or detail, how do, the rest of us, understand a cooling Load Calculation?

My advice is to look at the out door design conditions that must be factored into the calculation.  For cooling, ACCA Manual J has 6 outdoor conditions.

  • Two relate to location. Cooling in Atlanta, is different from Wichita and is different from Denver.
  • One is the outside temperature. The choice is a temperature that covers all but 1% of the hours in a year that require cooling for that location.
  • There are four design conditions that relate to Relative Humidity.

This obviously requires a balance. If your contractor varies from these conditions, it still must balance.  You may or may not like the balance, if one item is changed without consideration of the others.

What should you as a consumer do?

Insist that professional standards be used.

Require that all the items of the standard be measured and reported.

For Air Conditioning the standards require measurements of:

  • Air Flow Actual compared to manufacturer’s requirements. (+/- 15%)
  • Air Flow Static Pressure (ESP)  Actual within the manufacturer’s acceptable range
    • AND
  • No more than 25% or 0.10 IWC over the design pressure for the duct system.
  • Refrigerant Charge Verification
    • Superheat method:  Within +/- 5% of manufacturers superheat value.
    • Sub cooling method: Within =/- 3% of the manufacturers subcooling value.
  • Measured line voltage and low voltage circuits for voltage and amperage. These values shall be within the manufacturer’s requirements.

If you have good air flow in some rooms and not enough air flow in other rooms, your home has an air balancing problem. Have your system checked and balanced. This is known as test and balance or TAB. I have done test and balance work. Generally, the air flows should be within 20% of the design or application requirements.

Quality Installation and Maintenance of HVAC Equipment

The news this month has multiple stories about Heating and Air Companies being very busy with units not cooling or not cooling enough.Screen Shot 2016-06-24 at 8.49.56 AM Driving around town, I see most of these contractors have a sign out front looking for help. The wait time is up to two weeks.  In the 7 homes I’ve been in this week.  One had no working AC, one home was on it’s last legs, and two other homeowners were very concerned. For the 1st time in 7 years, I’m getting calls from my website asking if I can fix their AC unit.

This morning I found a report on HVAC Problems, Problem Identification and Repair.  I have scanned this 27 page report and these are the things that jumped out.

Background:  California has some of the toughest energy requirements for buildings, both new and remodeling of existing buildings. These is a direct result of the problems they had 15 years ago, with not enough electricity.  They resulted to black outs, (Utilitys were allowed to shut off electricity to various geographic areas).  and brown outs, (Utilities were allowed to provide only part of the electricity needed to a geographic area).  Both are not good.

These energy codes are generally referred to as Title 24.  A large part of the work in California the last few years has been testing and measuring how well the requirements are being met.  This report is just one small piece of that process.

Title 24 refers to the problems, their identification and repair as “Fault Detection and Diagnosis” or “FDD”

Screen Shot 2016-06-24 at 8.51.18 AM

The Report was working on the answers to these questions

  • Is FDD worth the investment, and what is the savings potential?
  • How effective are available FDD methods and what do they cost to implement?
  • What training is needed for effective FDD and is it being provided?
  • Are codes and standards working?
  • What are the major gaps and how can they be addressed?

This particular session and reporting was limited to:

 

  • System Types–new and existing residential only
    • Air conditioners
    • Heat pumps
    • Furnaces and air handlers
  • Fault Types
    • Low airflow
    • Refrigerant system charge, restrictions, and contaminants
    • Mechanical and electrical faults and faulty installation
  • Repair vs. Replacement Issues
    • Cost-effectiveness of FDD
    • Replacement refrigerants for R-22
  • Human Factors
    • Training and quality of maintenance
    • Homeowner knowledge and expectations.

The reporting included tests applied with standard AHRI methods. The tests were designed to determine the impacts on efficiency and capacity of a variety of conditions, including:

  • Airflow of 250 cfm/ton reduced energy efficiency ratio (EER) by 12% and has the potential to produce a false overcharge diagnostic due to freezing of the coil (the asterisk denotes an unofficial EER)
  • Liquid line restrictions (e.g. due to clogged filter-dryer or metering devices) reduced EER by 30% to 36% for non-TXV and TXV systems respectively
  • Only 0.3% Nitrogen in the refrigerant reduced the EER  by 18% with no TXV and 12% for the TXV-equipped system

Discussion pointed out that California Title 24 charge verification methods, which only measure superheat (for non-TXV) and sub-cooling (for TXV) systems, and ACCA Standard 4, for which only 3% of the procedures are related to energy performance. Also covered were  how improperly maintained vacuum pumps, test instrument error, and poor service practices such as use of rules of thumb contribute to the introduction of non-condensables, improper charge, and other faults.

John Proctor, PE presented a case for making improvements to California’s Title 24 standards, John worked with a team to inspect a large number of recently built homes to identify HVAC installation and performance issues. He began his presentation by defining an “incremental effectiveness ratio” that divides benefits of maintenance by the incremental cost to diagnose, repair, and ensure quality, which is fundamental to the question of the value of HVAC service. He proceeded to show a series of graphs from his experience and other studies that illustrate the deviations from the ideal for airflow, charge, duct leakage and efficiency, and non-condensables, as well as the incidence of occurrence of these defects.

For example, his graphs show:

  • 50% reduction in airflow reduces EER by 25%.
  • A refrigerant charge that is 70% of the recommended charge reduces EER by about 55%.
  • Leaving Nitrogen in the line set and coil at 20 psig before charging with refrigerant reduces the sensible EER by about 45%.
  • From his 2003 survey, more than 60% of the houses checked failed on refrigerant charge, airflow, and duct leakage, and more than 95% failed overall.

Many of these issues result from a lack of training and a lack of follow up by supervisors.

They had some specific things that could be done by builders, HVAC Contractors and home owners to ensure these items do not get missed.

I will read the report in more detail and have further comments.

You may read the entire report.

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.

‘Show Your Work’ Isn’t Just for Math Class Anymore

percent greenMy wife is a Math Teacher.  She always likes student’s papers that ‘show your work’! This NAHB Report says ‘Show Your Work’ also applies to building and selling Energy Efficient Homes.

An Early Look at Energy Efficiency and Contributory Value examined sales of homes in the greater Denver metropolitan area between January 2012 and April 2014 to determine the impact that energy efficiency has on the home buying process.

Ultimately, the authors concluded, “There is a current lack of researchable and quantifiable data … Until the data is consistently available and easy to find, it is likely that the residential appraiser’s ability to develop a credible opinion of value will be limited.

Among the observations/findings in the study:

  • The percentage of home sale listings citing “energy” increased in both local multiple listing services between 2006 and 2013, apparently indicating that such features are increasingly appealing to prospective buyers.
  • DadBabyESIn a very limited survey the authors conducted of home owners who purchased Energy Star-qualified homes, 96% indicated that if they were purchasing a home in the future, they would like the home to have an energy-efficiency rating so that they could compare it to other homes.
  • According to the authors: “Appraisers need third-party certified and verified energy-efficiency documentation.” Determining a home’s energy efficiency is “beyond the normal scope of work,” knowledge and experience of an appraiser.
  • Although the survey was not intended to estimate property values based on the presence of energy-efficient elements, in most of the case studies, the presence of energy-efficiency features added measurably to the value of the home. Several of the homes featured in the case studies were certified to the ICC 700 National Green Building Standard.
  • It was difficult, and sometimes impossible, for the study’s authors to separate the value of energy efficiency measures from other green features.

NAHB actively supports efforts to educate appraisal and realty professionals about the intrinsic value of home performance, and how certifications like the ICC 700 National Green Building Standard can help non-building professionals and their customers identify high performance homes and appreciate their benefits.

Full Report

Buying an Energy Efficient Home

HomePOHThe Annual Spring Parade of Homes is on the last week in the Wichita Metro Area.  There are some great homes out there. Lots of amenities to consider. Everyone has their own lifestyle and looks for a floor plan to fit. They all have their sense of taste and can look at the colors, finishes and visual effects.

POH_S15Every builder says they build an energy efficient home. Energy Efficiency is built in behind the walls.  It is usually not seen.  Energy Efficiency is about people and how they install the items that create the efficiency.  The specific items are less important then the way they are installed. Generally, the manufacturers install instructions must be followed.

Wichita – Sedgwick County has not adopted any code provisions for energy efficiency in new homes.  It may be legal to build a home with no insulation, but is that a wise decision? No one thinks so.  So how much is enough and is it installed correctly?  In this area we are reliant on the free enterprise approach energy efficiency in new homes.

Phoenix, AZ has an energy code, yet the free enterprise market based system has upped the game for buyers.  Here is a recent article in the Phoenix Newspaper about how a home buyer can see what is behind the walls.

Arizona-Republic-Features-of-ENERGY-STAR-HERS

Coca Cola to narrowly miss HFC-free global refrigeration target

The Soft drinks giant will miss its target, set in 2009 for including natural refrigerants in all new equipment globally by 4 per cent,

Coca Cola will narrowly fail to reach its ambitious target of only using natural refrigerants – primarily carbon dioxide, but also hydrocarbons – in all its new vending machines globally by 2015. The manufacturer’s sustainable refrigeration manager Antoine Azar told the audience at the Atmosphere conference in Brussels that there remained a 4 per cent ‘technology gap’ in the smallest vending machine sizes.

The drinks giant now has 1.4 million HFC-free vending machines, a 20 per cent rise over the previous year, Mr Azar said, with 78 per cent of models performing more efficiently than HFC units,

To read the full story

New Efficiency Standards for Hot Water Heaters

The National Association of Home Builders has condensed the DOE page on the new Efficiency Standards for Hot Water Heaters. The good news is if you buy the unit, you can install it, until existing stocks are used up. There are also some alternatives in specifying and installation you can consider.

Elec DHWNew residential water heater energy-efficiency standards that go into effect April 16 will require changes to the installation of many residential water heaters. Most water heaters with a capacity of 55 gallons or less will require more installation space, and those larger than 55 gallons in capacity will see additional, more significant changes. However, products manufactured before April 16 can still be bought and installed after the changeover date.

These new efficiency standards will require much higher Energy Factor (EF) ratings for larger water heaters, making a huge impact, especially on how these types of water heaters are manufactured, distributed, installed and/or vented.

PV DHWThe more common-sized water heaters of 55 gallons or less will likely be larger by roughly 2 inches in height and diameter to account for the additional insulation needed to meet the new standard. This may require builders to account for the increased size in their design.

It is expected that replacement water heaters installed in closets will present the biggest problems: They may require installing an applicance with reduced water capacity, selecting a much taller tank of the same diameter or a switching to a tankless water heater if space does not allow for a simple change-out.

As more information is available from manufacturers and the federal Department of Energy, NAHB will update this page.  Continue Reading

Be Proactive for a Green Appraisal

greenlightbulbWhen it comes to getting an accurate appraisal for a high-performance home, it’s easier and more practical to take the right steps up front than to try to get a low appraisal revised after the fact.

Appraisal expert Sandra Adromatis, a featured speaker at the High Performance Building Zone during the recent International Builders’ Show, offered advice for securing an accurate appraisal of a high-performance home.

First and most important is documentation, especially of features behind the walls and other items that aren’t immediately obvious.

A good place to start is by taking a close look at the Appraisal Institute’s Residential Green and Energy Efficient Addendum. This is particularly important if the home is built to a nationally recognized program like the ICC-700 National Green Building Standard or includes additional high-performance features that should be documented within the appraisal.

This article appeared on the NAHB Blog.

For the complete article

Ms. Adomatis also presented at the RESNET Conference after the IBS Show. I furnish the Energy portion of the AI Energy Efficient and Green Addendum for every new home rating I do for a builder.  If you would like to see one or see how it would help your building plans, give me a call.

WWII and Energy Efficiency of an Office

Enigma-Machine1Occasionally, my long time interest in History and my job intersect.  Here is a news story that does. The headline “Top Secret Documents found in roof at Bletchley Park”, so I naturally read the article.  Bletchley Park during WWII was a great part of the secret  war effort by Great Britain against Germany.  It was run by His Majesty’s Government Code and Cypher School, to read coded German messages. It is named for the landed estate it was located on and has been turned into a museum. Location.  This is about 60 miles or 100 km NE of London center near the M1.

hut 3The connection to Energy Efficiency is these documents were found stuffing into openings in the roof of ‘Hut 3’  The huts were quickly built barracks type structures built early in the war, and did not have many amenities, even for the time.  Things like insulation, central heating, or probably much in the way of wall board on the inside. So these buildings leaked.  I would guess these very smart, talented folks working in Hut 3, didn’t know much about energy efficiency.  They did know when they were uncomfortable and could feel the wind blowing through the cracks and crevices.

So they took what ever was handy and stuffed the cracks full to stop the wind.  Today we call that air sealing.  These are the guys that invented some of the first computing machines. The solution was, like many of the wartime efforts, not the most elegant, but it worked.

If you would like some help locating the air leaks in your home, give me a call. I’ll use a Blower Door and a computer that is a descendant of those in Bletchley Park.

You can read the whole story here.

Passive House Verifier Training Part 1

PHIUSPHIUS (Passive House Institute United States) is one of two organizations in the US that promote and issue certificates for completion of a home that uses extremely small amounts of energy to heat and cool a home. The other organization is an affiliate of the German PassivHaus Institute.

This organization is based in Illinois. The goal is to make passive building principles the mainstream best building practice, and the mainstream market energy performance standard.

prosocoWhat is a Passive House? It is a home that people want to live in. It must be comfortable for the occupants and it must use very small amounts of energy to heat and cool; and for total energy use as well. RIGHT: A Passive House under construction.

Design for a Passive Home emphasizes energy efficient features that are installed during the construction of the home which do not have moving parts. The design relies on all parts to be installed to manufacturers specifications. These details are verified after they are installed.

Smith HouseThe idea is that insulation and air sealing are very cost effective compared to large and sometimes complex new technology in HVAC Systems. Instead of buying the expensive technology, use the money, that would usually spent on upgraded HVAC system, to increase the insulation levels. The details of how much insulation, what type and where are certainly of interested to  the builder and others involved in planning and construction. These details are less important to the home buyer, they just want things to work at a lower cost.

I am writing about Passive House construction since I just finished the training and testing to become a Passive House Verifier with PHIUS. You will hear more about the Passive House concept and how it might apply to any home.