Posts Tagged ‘health’

Garden Fresh Salad

June 30, 2017

The problem is adjectives – adjectives and reality TV shows.  Garden fresh salad sounds much better than . . . salad.    Crisp green lettuce.  You can almost feel the crunch.  The same thing is true for people.  When we start calling people lying this and crooked that, itfresh-garden-salad defines the message that is coming next.  Which, of course, is exactly the point. But how can you have a civil and productive conversation with someone or about something if you’ve smeared it with a negative adjective?  The objections to some person or cause should be defined by the facts.  Facts are nouns.

What if the Declaration of Independence was peppered with adjectives?

When in the marvelous Course of wonderful human events it becomes necessary for one outstanding people to dissolve the crooked political bands which have connected them with another who is slimy, no-good, and worthless and to assume among the exceptional powers of the gonna-be-wonderful earth the separate and equal (and in our case, winning) station to which the Laws of Nature and Nature’s God entitle them, a decent (but unnecessary) respect to the fake opinions of mankind requires that they should declare the brilliant-just-and-truly-wonderful causes which impel them to this radical but excellent separation.

And if some event or participant is the winner then some other event or participant is the loser.  Winner and loser are also adjectives driven into popular vernacular by reality TV shows.  We need to stop thinking in terms of winners and losers when it comes to national policies.  A great school system is great for all.  A great health care system is great for the entire system in so many ways.

A country and the passage of time is NOT a TV show.  This is a country of people, citizens, people living and working and pursuing happiness and liberty together.  Not as Republicans or Democrats or Independents or some other party or affiliation or religion, but as Americans.  A Senator in Massachusetts or Georgia or Montana represents the citizens of that state, but they also represent the citizens of the United States.  And that is THE important adjective: UNITED.


What is my house doing to me?

November 22, 2016

Fall River, MA

hhe-kitchen-hazards“Why do I wake up in the morning with a headache?”  “Why is the house so dry in the winter?”  “What are VOCs?”  “Does my house have a radon problem?”  Can you answer all these questions?  When we do an energy audit on a home, we are looking for issues that impact the heating and cooling loads.  But the same tools that we use for thermal analysis can be used to highlight unhealthy or hazardous conditions in a house.  The BPI Healthy Home Evaluator (HHE) certification merges energy efficiency and home health together.

On Tuesday the 15th and Wednesday the 16th of November, a first in the nation BPI HHE class was held at Bristol Community College.  The BPI credential was developed in partnership with the Green & Healthy Homes Initiative.  “It builds upon the BPI Building Analyst (BA), Energy Auditor (EA), and/orbpi-logo-4c Quality Control Inspector (QCI) certifications to verify competencies required to conduct in-depth healthy home environmental risk assessments.  The Healthy Home Evaluator assesses home-based environmental health and safety hazards and provides a prioritized list of recommendations to address those hazards.”

The two day class extensively reviewed numerous aspects of HHE skills including the liability issues involved in stepping into a hazards and health analysis, resident interviews, the identification and interpretation of hazards, and the seven “Keep Its” developed to clarify the primary elements of the program:

Keep it:

  1. Dry
  2. Clean
  3. Safe
  4. Ventilated
  5. Pest-free
  6. Contaminant-free
  7. Maintained

The class was able to apply these techniques to the test cabin located in the BCC weatherization laboratory while going through a typical field analysis incgas-leaksluding gas leak detection, CO monitoring, combustion safety testing, blower door testing, and ventilation system verification.  Added to these was asbestos pipe insulation, messy counters including cigarettes and spilled coffee, long blind cords, children’s toys in the oven, toxic chemicals in a cabinet, and a hazardous carpet.  These hazards were so common and obvious that the students missed many of them despite the fact that they had been sensitized to seeking them out.  Like odor fatigue, elements such as these are so common in an energy audit that they are simply overlooked.

What are the Lower Explosive Limits for natural gas, propane, and gasoline?  What is the impact on house pressures of a blocked return air vent?  Is it a water stain on the ceiling or sign of a mouse nest in the attic?  There are dozens of questions about a house.  Some of them are no problem at all.  Some of them are chronic, long term problems, and some of the are acute problems (like CO) that should be addressed immediately.

This is an evaluation credential.  There is so much to know about this stuff that it will take years of testing and experience to know the ins and outs.  But if we can get homes safer and healthier it will save a great deal on medical care which should appeal to health insurance companies and all of us.

If you wanbristol-community-college-1t to learn more about this stuff, Bristol Community College will be conducting more of these classes at 1082 Davol Street, Fall River, MA 02720 – 774-357-3644

Healthy Home Evaluator Training

October 13, 2016

Fall River, MA     October 13, 2016

hhe-class2_troost-avenue For two days – November 15th and 16th – Paul Raymer of Heyoka Solutions will be teaching a pilot of the BPI HHE course at the Fall River campus of Bristol Community College (BCC).  The purpose of this course is to blend the knowledge of building science with the ability to recognize home environmental risks.

For years qualified building scientists have been striving to make homes more energy efficient.  The same tools can be used to recognize a healthy home environment.  Using their building science knowledge, students taking this course will connect what they already know to environmental concerns that are being overlooked.  The class, based on a course developed by Healthy Housing Solutions, is a combination of classroom sessions, group exercises, hands-on tool use, and situation analysis in BCC’s unique test cabin.  This class will review basic building science fundamentals and analysis tools that are used to apply the six Keep It principles: Keep It Dry, Keep It Ventilated, Keep It Clean, Keep It Pest Free, Keep It Safe, and Keep It Contaminant Free.

What is Integrated Pest Management?  What if the homeowner says the house is too dry?  What does that mean for energy use?  What does that mean for health impacts?  What impact do air fresheners have on the environment?  What impact do they have on energy efficiency?  What elements of a home environment might impact asthma in children?  What issues are chronic?  What issues are critical and an Immediate Danger to Life?

Consider healthy home evaluation an investigation, like CSI.  Understanding building science fundamentals can be lead to a clarification of a healthy environment.  A house is a system.  It’s all connected.hhe-class1_troost-avenue

Upon completion of the course students will be ready to challenge the BPI HHE 1.5 hour certification exam offered on November 17th.  Class will be held at  BCC – 1082 Davol Street – Fall River, MA  Phone: 774-357-3644

Contact Rosemary Senra at BCC for more information.

If we’re going to do the job at all, we might as well do it right!

March 2, 2015

Gas ChecksDespite our best intentions, everybody makes mistakes.  It may be from lack of knowledge.  It may be from laziness.  It may be from just not paying attention.  Some mistakes have no consequences.  Some mistakes can kill people.  There are a lot of skills that go into making a house more energy efficient.  You can learn the fundamentals of the laws of thermodynamics and how to operate a blower door or an infrared camera, but the only way you gain wisdom is through experience.  When you are in  a crawl space sealing up the ducting joints and there is one more joint way back in the corner that no one will ever see except you  and it is damp and dirty and you’re lying on the floor covered with building rubble, are you going to go back there and get the job done?  Are you just going to work your way back out of there, shrug your shoulders, and justify it to yourself?  That’s what KSA means: Knowledge, Skills, and . . . Attitude.  Some people say it’s Knowledge, Skills, and Ability.  And you do have to have the ability to get the job done.  But you also need to have the right Attitude.

Quality Control Inspectors are the last line of defense.  They must have the right attitude.  The energy auditor checks out the house and creates the work order.  The crew comes in with the crew leader and gets the job done.  The quality control inspector makes sure that the ‘i’s‘ are dotted and the ‘t’s‘ are crossed and . . . that last connection in the crawl space is sealed.  Sometimes the QCI is called in because there is a problem like excessive humidity on the windows.  Sometimes is just a matter of signing off on the job.  If everyone did their jobs perfectly, QCIs wouldn’t be necessary.  And who’s going to check the QCI?d

The BPI Home Energy Professional (HEP) certifications take a lot of knowledge, skills, ability (attitude), and experience.  You have to prove that you know a lot about a lot of things.  To assist in that process, I am creating a Quality Control Inspectors Handbook.  The National Renewable Energy Laboratories (NREL) Job Task Analysis (JTA), what the certification is based on, covers a lot of fundamental and soft skills.  The book will go through all the Domains and Tasks in the JTA as well as all the elements that are included in the BPI field exam.  There is a need for more QCIs to meet the states’ Quality Work Plans.  My goal is to provide a resource that can support these efforts.  If we’re going to do the job at all, we might as well do it right!

If you would like to stay updated on the progress of the book, click on Keep Me Updated!  QCI Handbook Cover copyThank you.

Sleepy From Turkey CO

November 26, 2013

I have been forced to leave more houses during energy audits because of gas ovens than for any other reason.  A gas oven burns gas.  Anything that burns can generate Carbon Monoxide or CO.  The combustion fumes move up through100_2776 an opening or chimney that generally vents just below the control panel near the burners.  If you hold your hand there, you will feel the warm, moist combustion air leaving the oven.  If the oven is old, dirty or mis-adjusted, an excessive amount of CO will get produced when the oven is being used.  The CO level is particularly high when the oven is first turned on (commonly over 1,000 ppm)  and should decrease as the system achieves a steady state operation (dropping to around 100 ppm or less).  It is advisable to keep the range hood running and venting to the outside or a window open slightly while using the oven.  CO has about the same molecular weight as oxygen so it is neutrally buoyant, but I would keep the infants out of the kitchen while the oven is warming up.

A well-adjusted gas oven flame should be blue in color, symmetrically shaped, and about ½ inch tall.  A ragged, hissing flame indicates the combustion process is getting too much air.  A yellow orange flame indicates it is getting too little air.  The flame should be continuous along the length of the burner.   If it’s not, some of the ports may be clogged, but make sure the oven is turned off and cool before making any adjustments.

I have always heard that people get sleepy from the tryptophan in the turkey, but I have begun to wonder if it’s the CO from the oven!  Enjoy Thanksgiving, but make sure your kitchen is properly ventilated!

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Ventilation and Health

January 31, 2013

Sleeping StudentThere are a lot of grumblings about a requirement to add mechanical ventilation to homes.  When we gather around the campfire on a starry night, there isn’t a need for mechanical ventilation.  When we bring the campfire into the building, we a flue to take the smoke and pollutants out.  And we also bring a lot of other things into the house including the dogs and cats.  And we cook in the house and generate a lot of moisture by taking showers.  We even bring plants inside to make it feel like we were still outside.  And we tighten up the house to keep it warmer in winter and cooler in summer.  So we’re not out under the starry, starry night any longer.

Okay, but is the indoor environment really hurting us if we don’t have mechanical ventilation?  In a dry climate like Nevada, is there really enough of a humidity problem to need mechanical ventilation?  Although it is difficult to study the relationship between mechanical ventilation and health, studies do exist.  Just this morning on MSN there was an article about “20 things that are making us dumber”.  Along with “Honey Boo Boo” and excessive email that we have to check on our “SmartPhones” every 90 seconds, was “Poor Ventilation”.  The article said, “Excess carbon dioxide is doing more than wrecking our climate – it’s also making us stupid.  Researchers at Lawrence Berkeley Livermore slowly increased the amount of CO2 in a poorly ventilated room while college students attempted to solve a series of complex, strategic problems.  Not surprisingly, the more CO2 in the atmosphere, the more mistakes the test subjects made.”

In a paper in Indoor Air entitled “Ventilation rates and health: multidisciplinary review of scientific literature”, a group of very knowledgeable researchers reviewed 27 papers published in peer-reviewed scientific journals.  Their conclusion was that “there is biological plausibility for an association of health outcomes with ventilation rates”.  They also said that, “Home ventilation rates above 0.5 air changes per hour (h-1) have been associated with reduced risk of allergic manifestations among children in a Nordic climate.”

In another Indoor Air paper entitled “Association between substandard classroom ventilation rates and students’ academic achievement”, researchers from The University of Tulsa, the Illinois Institute of Technology, and the National Institute for Health and Welfare in Kuopio, Finland studied the relationship between classroom ventilation rates and academic achievement.  They determined that, “There is a linear association between classroom ventilation rates and students’ academic achievement”.

Pine Tree air freshenerSomething else to think about.  The global market for air fresheners is forecast to reach US$8.3 billion by the year 2015. Growing consumer inclination towards fragrance products such as candles for decorating their homes is poised to propel the air fresheners market.  [Global Industry Analysts, Inc.]  (Candles also put out CO.  I’m just saying.)  Air freshener advertising puts people in rooms with wrestlers and brags about how fresh it smells!  If there are no pollutants in our air, why are we spending so much money to cover them up?  In an article in the University of Washington News entitled “Toxic chemicals found in common scented laundry products, air fresheners” author Hannah Hickey says, “”Be careful if you buy products with fragrance, because you really don’t know what’s in them. I’d like to see better labeling. In the meantime, I’d recommend that instead of air fresheners people use ventilation, and with laundry products, choose fragrance-free versions.”  Her study showed, “58 different volatile organic compounds above a concentration of 300 micrograms per cubic meter, many of which were present in more than one of the six products. For instance, a plug-in air freshener contained more than 20 different volatile organic compounds. Of these, seven are regulated as toxic or hazardous under federal laws.”

I have a control on my own ventilation system that uses a sensor that was developed in Japan to react to the chemical soup emitted by cigarettes.  No one smokes in my house, but there have been numerous times when the control has activated the fan when I can’t smell anything foul in the air and I have to wonder why it is operating, but I’m glad it is.  Our homes are full of stuff that we shouldn’t be breathing.  Is it worth betting your long term health and that of your children to save the cost of a fan?

(Copies of these articles are available upon request.)

Homeowner’s Energy Workbook – Part 9 Total U Value

January 14, 2013
Cottage Front

Cottage Front

We know that the primary heat losses for the house come from conductive heat flow (heat moving through the structure molecule by molecule from the hot side to the cool side) and convective heat flow  (heat carried around by all the airflows moving in an out of the house).  We know that a U value is the ability of an element to conduct heat.  We can add up all the conductive U values for the walls and windows and doors and ceilings and such, and we can estimate what the convective U value is for air leaking in and out through all the cracks and holes.  And we can add all those U values up to come up with a total U value for the house.

That number is reflected in how much energy your house has used to stay warm and how cold a year it has been (which we know from the Heating Degree Days).  This particular house is in Falmouth, Massachusetts.  The degree days for this past year are:

Month Heating Degree Days
January 732
February 733
March 538
April 419
May 181
June 84
July 3
August 3
September 65
October 215
November 606
December 572
Total 4151

We can determine the Total U value for the house from the formula:

Heat Energy Used/(HDD x 24)

It’s pretty simple:  There are 24 hours in the day and when it’s colder outside, the house uses more heat!  We know from the gas bill, that a total of 37 therms were used in January.  Last week, we figured that about 5 therms per month are used for cooking and the heating hot water for the shower.  The house used 37 – 5 or 32 therms for heating in January.

We have to step back here for a second and address the fact that the heating system is not 100% perfect.  When the gas furnace burns the gas, some of that heat goes up the chimney.  Some heat is lost because of an imperfect duct system – missing insulation or leaks in the joints.  So in this case the system is about 80% efficient (that’s a reasonable average).  So if a therm of natural gas has a potential 100,000 BTUs, only 80,000 are being delivered in this house.  So in January, the house used 32 x 80,000 or 2,560,000 BTUs for heat.  Dividing that by the HDD times 24 gives us a Total U value for January of 145.7.  We can do that for the whole year and come up with an average, Total U value for the house.

Month Heating Degree Days Therms Used (Part 8 Bill)
U Value
January 732 37 – 5 = 32 146
February 733 44 – 5 = 39 177
March 538 41 – 5 = 36 233
April 419 25 – 5 = 20 159
May 181 8 – 5 = 3 55
June 84 7 – 5 = 2 79
July 3 0[1]
August 3 0
September 65 0
October 215 0[2]
November 606 16 – 5 = 11 61
December 572 29 – 5 = 24 140
Total 4151   Average: 130

The total U value for this house is 130.  That is the sum of the heat loss through all the structural components as well as the convective losses.  What can you do with that number?  If you are planning on making improvements to your house, you can monitor the changes to the total U.  If insulation is being added to your attic or you are going to replace some windows, those improvements should reduce the total U.

When you figure out the U value of individual components, you can use that information to determine if an improvement is going to pay off or not.

Next time: Component U Values

[1] Months that are equal to 0 aren’t included in the average Total U value calculation because there is no heat loss.

[2] Note that the gas bills do not cover exactly the same days as the HDD calculations, but it averages out.

Homeowner’s Energy Workbook – Part 7 – The Skeleton

December 31, 2012

You need to get familiar with the skeleton of your house.  Most of our houses are framed with studs, commonly known as two by fours or two by sixes.  These are pieces of wood that have been milled from trees that are nominally 2 inches by 4 inches on a side.  (The milled pieces.  Not the trees!)  They used to actually be 2 inches by 4 inches, but with the fancy milling that goes on in saw mills, they are now one and a half inches by three and half inches or one and half inches by five and half inches.  This is important because there is now less space in the wall for insulation and other stuff.

Balloon Framining

Balloon Framing

Up until the late 1940’s the wall studs ran all the way from the foundation wall up to the attic framing.  This is known as balloon framing.  The studs had to be really long to go that far.  It’s handy for running wires in wall cavities, but it forms a chimney up the outside walls of the house.  The rising air (convection) can flow all the way up from the basement to the attic!  And with open floor cavities, it can even flow under the floors and up the inside walls.  This can make the inside of the house really uncomfortable.

Both because we had harvested most of the easily accessible, tall trees an because it is more convenient, since that time we have been using a platform framing technique.  Each level gets constructed individually.  The deck of the second floor serves as the platform on which to build the walls.  This technique makes the stud cavities in the outside walls shorter, limiting the convective loops.

If you start in the basement (assuming you have a basement), the Rim joist is at the top of the basement wall, connecting all of the first floor floor joists.  On top of that is the stud wall, reaching up to the Band joist that runs around the middle of the house, between the floors, connecting all the second floor floor joists together.  Then the second floor stud walls reach up to the ceiling rafters (unless you have a third floor).  The ceiling rafters form the ceiling plane, the top, inside surface of the house.  The roof is commonly framed with Trusses these days that are often built off site and trucked in.  In many cases the roof is framed with individual two by lumber on site.


Thermal Envelope

The Building Envelope is a term for all of the materials that separate the inside space from the outside space.  It includes the walls, windows, doors, floors, and roof.  Part of the building envelope is the Thermal Envelope or Thermal Barrier.  The space inside that is what is conditioned – heated and cooled.  It is the conductive heat barrier or blanket keeping the occupants comfortable.

Aligned with the Thermal Envelope is the Pressure Envelope or Pressure Barrier.  This is the convective heat/cool barrier.  The key to a comfortable living space is for the Thermal Barrier and the Pressure Barrier to be working together, to be aligned.  This is a really important issue that we will get into in more detail later.

I want to go back to that “house as a system” idea.  The floor, walls, ceilings, roof windows, doors are all part of the system. Except in “paradise climates” a house missing the windows would obviously not keep the occupants very comfortable.  If the walls were missing, that wouldn’t be much of a house either.  These are the extreme, and gratefully uncommon, conditions.

Let’s consider a house heated with fuel oil on a cold winter day.  If the oil runs out, the furnace can’t burn to produce heat.  The house cools.  If it gets cold enough, the water in the pipes starts to freeze.  As the ice in the pipes expands, it cracks the pipes.  When the outside temperature warms, the water melts and shoots out of the pipes, getting the walls wet.  The wet walls are a perfect breeding ground for mold growth.  And so on, and so on.

Again, this is a somewhat extreme system connection.  There are millions of much more subtle connections that are going on all the time in houses.  Many of them don’t mean much on a human time scale, but as houses get more efficient, the interactions, the systems become increasingly more interrelated, and the potential problems are amplified.  So we always want to ask before we start changing something, “What else is going to change if I do this?”

One of the things I have found living in an older house, is that one remodeling project seems to lead to a dozen more.  Changing a sink may require replacing the vanity, the pipes, the drain in the floor, the color of the bathroom walls, the floor covering, the towel racks, the lighting, and on and on.  The system unfolds before my eyes and a Saturday project becomes a Fall project!

Homeowner’s Energy Workbook – Part 6 (Definitions)

December 24, 2012

Stack effect on a Fireplace

Infiltration and ex-filtration relate to convective air movement.  Infiltration is uncontrolled air leaking in and ex-filtration, logically, is uncontrolled air leaking out.  How and where it leaks in has a lot to do with the pressures in the house.  (Remember, high pressure moves to low pressure.)  If the pressure is higher in the house than it is outside, air will move out of the house.  Warm air is lighter than cool air so it rises, increasing the pressure at the top of the house due to the Stack Effect when it is warmer in the house than it is outside.  The top floor ceiling of a house can have an enormous amount of pressure pushing on it, pushing air through any crack or hole or gap it can find.

A wise building science guy, John Tooley, once said, “Air is like crooked rivers, crooked people, teenagers and cheap labor.  It always seeks the path of least resistance!”  He also said, “Air doesn’t care where you want it to go.  It will always move through the closest and biggest hole.”

We have to have ways to measure things like pressure and temperature and airflow.  We measure temperature with a thermometer.  In the U.S. we measure it in degrees Fahrenheit named after Daniel Gabriel Fahrenheit in 1724.  Most of the rest of the world adopted the Celsius scale (after Anders Celsius) in the mid to late 20th Century.  The Fahrenheit scale has water freezing at 32 °F and boiling at 212 °F.  On the Celsius scale, water freezes at 0 °C and boils at 100 °C.  Seems a bit more logical somehow, but there we are.  We don’t deal with change well.

The pressure in buildings is commonly measured in Pascals, because houses have gotten so tight and the pressures are so small that using the inches of water gauge or iwg or inches of water column scale was too gross.  It would be like measuring a house in fractions of a mile!  Inches of water gauge is an indication of how far a certain amount of pressure can raise a column of water.  Iwg is the most common measurement for indicating pressures in heating and cooling systems and the operation of fans.  One iwg is equal to about 250 Pascals.  The important thing to remember here is to visualize how small a Pascal is.  It’s really, really small.  If we could measure a gnat’s burp, it would be about that small.  It’s a tiny amount of pressure, but it can make an enormous difference in how a building works and the health of the occupants.  We measure pressure using a manometer.  These days it’s common to use an electronic, digital manometer, but there are analog manometers as well.  The availability of digital manometers probably has done more for the advancement of building science than any other tool.  It has allowed us to measure very small pressure differences.  It has ushered us into the world of CSI for homes.

Testo 417

Large Van Anemometer

Airflow speed is measured in feet per minute (fpm), like miles per hour.  FPM is the velocity of the airflow.  The volume of air movement is measured in cubic feet per minute (cfm).  The volume of air moving through a duct or fan is indicative of a rate of heating or cooling.  Airflow is commonly measured with anemometers which come in a wide variety of styles.  There are large vane anemometers and mini-vane anemometers and hot wire anemometers.  There is a tool called a Balometer which is commonly used to measure airflows in commercial applications.  Airflow can be measured with a garbage bag or a bathroom tissue, but the numbers are not easily repeatable with these approaches.  Airflow can be measured using a manometer as well, by using the difference in pressure across a known sized hole.

You should also be aware of some of the nasty elements that can be found in homes.  Carbon monoxide (CO), for example, can kill people.  It results from incomplete combustion.  If the flue gases don’t flow up the chimney the way they are supposed to, they can “spill” down into the house and make the occupants sick, exhibiting symptoms similar to the flu.  More about CO later.

Radon is a gas that emanates from granite in the ground.  Radon can leak into the house as a gas, and rapidly decay into particulates that can get lodged in the occupants’ lungs.  It can also be found in water.  It is much worse for smokers to breathe radon gases than non-smokers, but that is true of many things!  Certainly not every house has radon issues, and it can be tested and it can be reduced to acceptable levels.  And just because your neighbors’ house has a radon problem it doesn’t mean that yours does.

Humidity is another significant pollutant for a wide variety of reasons.  Relative Humidity (RH) is indicative of the amount of moisture a volume of air can hold at a certain temperature.  Warmer air can hold more moisture than cooler air.  As the temperature of the air rises, its RH goes down.  That’s why cold winter air drawn into a house makes the air in the house drier.  Cold air in a closet has higher relative humidity and mold grows on the cooler surfaces.  RH is not the easiest thing to visualize, but we can certainly feel it.  “It’s not the heat.  It’s the humidity!”  The dew point is the temperature of a surface that will cause moisture to condense.  As the dew point rises in warm weather, our discomfort increases.  When the dew point is only a few degrees below the outside temperature, it is almost hard to breathe.  It is interesting to note that there are microclimates all around us.  The air around a glass of ice water can be cooler and at the dew point and moisture droplets form on the sides of the glass.  This is similar to the microclimate convective loops in insulation gaps and on the surface of walls.  All this stuff is going on around you.  Right now!  And you thought things were just sitting there!

Just to be consistent, we measure relative humidity with a device called a hygrometer.  A humidistat is a control that turns something on when the humidity goes down.  A dehumidistat is a control that turns something on when the humidity goes up.

Next time: The Skeleton!


Homeowner’s Energy Workbook Part 3

December 4, 2012

P1000610But let’s go back to your house.  One of the most fundamental questions is where is it?  It’s pretty obvious is that a house in Alaska is going to perform differently than a house in Florida.  It’s probably going to be built differently.  It’s probably going to be conditioned differently.  It’s probably going to be lived in differently.  There has to be some metric that will help to define the environment surrounding the house.  We can’t just say a house in Alaska is subjected to “colder” weather than a house in Florida.  How much colder?  Ooh, a lot colder.  What does that mean?  Well we do have weather bureaus that track all sorts of weather conditions, and certainly temperature is one of them.  We could say that we want to keep our house at at least 65 degrees Fahrenheit so we keep track of how far and how often it falls below that.  In Hawaii, it doesn’t often fall below that, even in winter.  In Alaska it falls a lot below that and quite often!

Wait a second.  We know that high temperature goes to low temperature.  We know that if we take our hot supper outside when it’s 20 degrees out there, our supper is going to get really cold really fast!  So if the temperature in the house is 65 degrees and the temperature outside is 65 degrees, there’s not going to be any temperature change so we’re not going to need to add any heat to keep it warm.  As the temperature outside drops, the difference between the inside and the outside of the house gets larger and larger, the house loses more and more heat and needs more and more heat to keep it comfortable.

The weather bureau keeps track of the average temperature for each day and we can compare that to 65 degrees.  We can add up those differences and come up with what is called Heating Degree Days.  The more annual heating degree days, the colder the environment that our homes are subjected to.  In 2011 Anchorage, Alaska had 8432 degree days.  Key West, Florida had 6!  So obviously, a house in Alaska is going to require more from a heating system than a house in Florida.  We can do something similar for cooling.

Take a minute a go to the Weather Data Depot and plug in your zip code and find out the heating and cooling degree days. I would suggest that you set your balance point to 65 degrees.  A few degrees of heat are added by waste heat from appliances like your refrigerator and light bulbs, as well as the heat from people and pets.  65 is a good base point for the heating system to turn on.  (There are other degree day resources like that will also supply similar information.)

The numbers that you find in books are generally 30 year averages.  Those numbers are great for determining long term heating and cooling conditions.  The web site can give you recent heating and cooling degree days that you can compare to your own heating and electric bills to see how accurate your calculations are.