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Residential Energy Efficiency Blog

Air Changes Per Hour, Energy Efficiency & Indoor Air Quality
Monday, September 28 2020

Building science principles are fascinating. When it comes to Maryland residential indoor air quality it all makes very good sense and Maryland homeowners should have basic knowledge of three important things around the house and how they are connected.

Three building science principles every homeowner should know

  • Air Changes per Hour
  • Energy Efficiency 
  • Indoor Air Quality

Read on to learn how they all connect to one another...

Air Changes Per Hour (ACH)

Air changes per hour (ACH) can be defined as the amount of times the volume of air inside your home changes with the outside air.  It is the house "breathing" in effect. If your house is calculated at 7 ACH then you can expect that on any given day and during any given hour, the inside air will exchange with outside air seven times. 

ACH in new construction homes has to be very low (3 or less).  New building codes for energy efficiency are making builders install energy efficient measures at the time of construction so that all of the typical leakage points are sealed before walls and ceilings go up which makes those areas very difficult to treat after they are in place (like in preexisting homes).

Energy Efficiency - Controlled vs. Uncontrolled Fresh Air

But, when we tighten up the envelope and don't allow the house to "breathe" as much we have to find solutions to create the right amount of ACH for healthy indoor air quality.  The key to this is to make sure the introduction of fresh air into the building is controlled so that less energy is consumed to maintain good indoor air quality (the right amount of fresh air) rather than allowing it to infiltrate uncontrolled causing heating and cooling systems to work much, much harder.

Indoor Air Quality - What is it Actually?

So in considering indoor air quality, it is important to know that measuring indoor air quality is NOT to measure the amount of particles in the air.  Indoor air quality is actually making sure that a building has enough fresh air and in a manner that is cost-effective.  Good indoor air quality also goes a long way towards sustainability and the longevity of the buildings structural components.

Get Your Score Today - Home Energy Audit - BGE or Pepco

The best way to check your indoor air quality is to get a BGE or Pepco energy audit with Hometrust Remodeling.  We are certified to test and calculate your indoor air quality as part of your comprehensive energy audit.

An comprehensive energy audit is a great way to have your home evaluated.  Measures can be prescribed in a way that will address indoor air quality as well as energy efficiency and comfort.  It is the whole house approach that ensures that you can have the best indoor air quality and a less drafty house at the same time.

What do you think about the indoor air quality in your house?  We want to hear in the comment section below!

Characteristics of Maryland Houses with Winter Comfort Issues
Saturday, September 26 2020

If you live in Maryland long enough you will experience a cold winter. During extreme cold events most houses will give in to the "pressure" and feel drafty. The heating bills go up and your house may never feel warm. Before you know it the winter is over and you spent a whole lot, but you didn't end up getting much comfort in return.

Unless a home has a pressure boundary to go along with the thermal boundary then extreme winters will be costly and uncomfortable. The missing part of an insulated home is sealing up all places where air can flow from the outside to inside or inside to outside. Most Maryland houses are in this category and are considered to be leaky.

As certified professional home energy auditors with over 1000 home energy audits completed we understand the common configuration problems that cause issues for different style houses. Having this experience gives us good insights into how to solve issues and not make them worse.

Below are a list of characteristics found in the houses with winter comfort issues.

  • Recessed Lights in Top Floor Ceiling
  • Open Chimney Damper
  • Unsealed Attic Access Hatch
  • Fiberglass Batt Insulation Installed at Attic Floor
  • Closets with Doors to Attic Areas
  • Houses Built on Crawl Space
  • Homes with Kneewalls and Sloped Ceilings
  • Houses with Uninsulated Ducts
  • Poor Overall Attic Ventilation

To understand how to get a hold of the winter cold in your home, you must first understand the Stack Effect. The stack effect happens in every building and it gets its name from a chimney. The physics behind the name is that at the base of the chimney - the fire - there is a "pull" or negative pressure. At the top of the chimney the smoke and heat billows out. That is the "push or burst" - the positive pressure.

In the winter our heat in our homes rises upwards. Much like a hot air balloon. We all know that hot air rises. What we have been missing for all these years is that the hot air is escaping through holes in the ceiling. And when it gets pushed through the top it gets pulled in at the bottom (crawl space, untreated basements).

To make a Maryland home more comfortable in winter the focus must be on sealing the attic floor. Disruption to the flow of warm air escaping through the ceiling will also disrupt the negative pressure, or cold air streaming in at the basement. Less negative pressure means less cold air infiltration - or less drafts. By sealing the attic, the heat can't escape and the furnace/heat pump does not have to run as long.

An energy audit through the BGE Home Performance with ENERGY STAR program is a great way to get up to speed. An energy audit, done with a great energy auditor, will guide you to how your home fares. Usually, we intrigue homeowners with easy to fix finds and advice that puts them in control.

In sports, one way to describe a team or a player that is peforming at peak is to say there is a "science" behind it.  When it comes to home comfort there is a true science behind it and Hometrust has the training, knowledge and diagnostic tools to test and finally get to the source of your home comfort issue.

Breaking Down a Pepco Energy Audit
Wednesday, September 09 2020

Often times homeowners don't know what a Pepco energy audit is or how it can actually help.

For starters, a Pepco energy audit can help you avoid choosing the wrong solution to a problem around your home. An energy audit through Pepco is a good place to start a home improvement priority list. 

Take the important step of scheduling your Pepco energy audit as soon as you can!

The Reason We Do This!
Friday, September 04 2020

Positive customer feedback!

Damp in your Basement? Here is the reason.
Friday, August 28 2020

Get to the Root of the Problem

A doctor always wants to get the the source of the issue. Let's consider a lower back ache as an example. If you hurt your lower back chances are the doctor will give you a muscle relaxer for the symptoms. A good doctor will likely give you a pamphlet on core strengthening exercises to get to the root of the problem.

Specialized Contractor Needed for Damp Basements

Some issues inside the home can be confusing and confounding for many contractors. A damp basement and high humidity are hard to solve.  As a homeowner, knowing where to turn for help might be difficult to figure out. Making matter worse, getting the wrong contractor can waste time or cost extra money.

Indoor Humidity and Seasonality

The recommended indoor humidity level - year round - is between 40-60%.

To get a handle on indoor humidity, the first thing to understand is the seasonality of indoor humidity.

In the summer the air outside is hot, humid and sticky in Maryland. We run our dehumidifiers in the basement. If you have not gotten around to attaching the hose most likely you are dumping water on the regular.  This effort pulls extra moisture from the air.

In the winter everyone talks about the Polar Vortex. Aside from being very cold, the Polar Vortex is also very dry! In winter our hands are cracking, lips get chapped and we need to introduce moisture into the inside air.  In this case a humidifier is used.

So, I will be clear. High indoor humidity is more of a summer issue.

Home Energy Audit

The key to solving a high indoor humidity issue is to look at it like a doctor. We need to find the source of the humidity in the air. We need to attack the problem. Where is the humid air getting in?  Waterproofing will not completely solve the issue.  Industrial strength dehumidifers are the muscle relaxer and treat only the symptom.

Having your home evaluated by a certified Building Analyst (BA) is a great way to identify home air leakage. It is important to understand that air leakage works both ways. Not only does air leak out of a house (exfiltration) air also leaks in (infiltration).

A blower door test can uncover air leakage points around a house.

Blower door testing in progress.

Working with a Building Analyst is a great place to start for a damp basement due to a high indoor humidity issue.

Thursday, August 27 2020

Did you know that at any given time there are around forty approved BGE contractors to do energy audits for Maryland homes?

Providing a comprehensive energy audit is a specialized service. It takes many hours of training, hands on experience and practice to give a good all around energy audit.

With so many houses in Maryland and so few BGE auditors how can you be sure to get a great auditor that hits on all points? After all, you only get the audit one time for the discounted price of $100.

Here are the questions you can ask the company (including us) you choose for your BGE energy audit:

1. How many BGE energy audits has the assigned auditor performed?

2. What is the auditors background before becoming an auditor?

3. What level of detail does the auditor plan to add to the energy audit report?

4. What is the physical condition of the energy auditor assigned to my house?

5. Is the auditor a good communicator and willing to engage?

Let's explore each of these questions a bit further.

1. How many audits have you completed?

Collecting the necessary data points during an energy audit is important. Having the repetition and experience allows a great auditor to assign time to the issues. If an auditor is new, taking accurate measurements may be a challenge. The auditor is learning on the job.

Everyone has to start somewhere, but do you want your one-time discounted audit to be the one? A great audit can unlock amazing concepts that will put you in control of comfort and energy usage.

2. What is the auditors background?

An energy audit looks at a house in a different way than a window consultation or roof estimate. An energy auditor is a three dimensional thinker whereas a window salesman has a one track mind. And, I am not even talking about making the sale.

An energy auditor needs to know a little bit about everything around a typical house. Having a background as a home contractor helps, but also being a homeowner is important. Experiencing and problem solving around your own home generates great learning experiences. These experiences along with learned concepts can go a long way towards helping you!

3. How is the final report going to look with a mediocre BGE energy auditor?

It is going to be a complete bore. The template for the BGE energy report is well designed and the information is good.

A great energy auditor will add details that pertain to discussions you had. Your BGE energy report final copy will be something you can keep for reference.

4. Should I really ask about my auditors physical condition?

Believe it or not, but doing a BGE energy audit the way it needs to is demanding work. An auditor must be able to get in small spaces, climb in attics and inspect crawl spaces. An auditor must be in good physical condition to perform a great audit.

5. Communication Pulls it All Together

An energy auditor needs to be so many unique things and on top of that if they are not personable, then it is a waste.

An energy auditor must be able to communicate key concepts in easy to understand ways. If the auditor cannot complete this task, the BGE energy audit could end up being useless.

5 Reasons Your New Windows Are Drafty
Friday, August 21 2020

It is not uncommon for homeowners that have purchased new replacement windows to be disappointed the next cold season because the new windows still seem drafty after installation. 

Here are five reasons why your new window replacement investment might leave you asking: 

Why do I have drafty new windows?


1. The Windows Were Not the Draft Source to Begin With

Often times windows get the blame for everything when it comes to home comfort.  This is somewhat confusing when considered through the lens of physics but not so much when considering the psychology of the window. 

The window is the part of the wall that we can see through.  If we hear something on the other side of a wall we assume that we hear the noise through the window.  If it is cold or hot and sunny, we can identify with the temperature by what we see.

On the other hand, physics and pressure and airflow dynamics tell a slightly different story.  There is no doubt that a window can be a source of comfort woes or energy in-efficiency, but so can hundreds of other points around a house and often times the worst offenders are places that you would not ever have imagined.

2. Understanding Stack Effect

The stack effect can be understood by thinking about a wood burning fireplace in a house.  At the base of the fireplace we place the wood and light the fire.  At the top of the fireplace is the chimney with a stack that usually rises up and above the roof for the hot smoke and ash to billow out.  In every fireplace a pressure dynamic develops when the fire is lit.  Stack effect diagram

At the base of the fire is the negative pressure.  A way to think of it is the fire sucking up oxygen to keep the flames ignited. 

The opening at the top of the stack is the positive pressure.  The smoke rises up and heads straight out. 

This stack effect pressure dynamic happens inside your home too.

Myths about new window drafts and comfort solutions can be unlocked by understanding the stack effect.  It is best to search at the basement level (base of the fire - sucking outside air in) and the top floor ceiling level of a house (top of chimney where conditioned air is looking for a way out!).

3. Fireplace Flue/ Recessed Lights

Recessed lights are the source of home draftsIf you just put brand new windows in and you still feel drafts, then look around a bit.  One easy way to find drafts is to look for the "gateways" to the outside. 

For example, one out of every five customers that I do an energy audit for do not have the flue shut on their fireplace chimney which is a huge gateway to the outside.  

Recessed lights are also gateways to the attic (outside) and if you have them and you had your windows replaced and your draft problem did not go away - there you go...

4. Improperly Treated Crawl Space/ Basement

Open crawl space vent.If the construction style of your home is on a crawl space that is open, then you might experience high drafts.  An open crawl space will allow unconditioned air into the the crawl space and unless there is a proper pressure boundary separating the foundation area from the room above, then drafts will surely occur through the floor.

If you have a full basement it is very likely that the rim joist in any finished or unfinished area has not been properly air sealed and this will allow air infiltration in the basement area that will cause drafts through walls and floors into the living space above.

5. Improperly Installed Windows

Another possibility, however the least likely, is that the new windows were installed improperly or worse yet, not caulked and sealed.  Even if this is the case, it would still be difficult to make a draft problem worse with new windows even if the windows are incorrectly installed due to pressure dynamics in a house.  It is important to note however, that basement windows and windows on the second floor could be susceptible to leakage if not properly installed and sealed due to higher pressure.

What can you do about this?

A great way to deal with the issue of drafty new windows is to have a comprehensive home energy audit performed.  An energy audit includes a blower door test.  A blower door test is an air leakage test on your house.  It is a large fan that pulls air out of the house.  When the air leaves at the front door new air replaces it from the holes and cracks around the house.  You can actually go around and feel around windows and feel around a recessed light air leakage testing new windowsand see for yourself that what I am saying is true!




Get a home energy audit in Maryland for $100 today!

Black Mold on Attic Side of Roof Plywood
Saturday, August 15 2020

Today's BGE energy audit (8/15/20) in Randallstown, MD yielded some great information that I want to be sure to pass along to as many people as possible because this stuff really makes sense!

The issue and original call came from a problem in the attic.  Mold stains on the sheathing (plywood).  It was discovered during the process of trying to find the source of water leaks that were showing up on the drywall ceiling in a few spots around the house.  The roof is 20 years old.

I have been in a lot of attics and seen a lot of plywood in attics (for which I am very proud!).  I wasn't sure about what I was going to find.  I have seen small patches of discoloration due to poor bath exhaust ventilation or a disconnected duct, but I have not had a mold case.  

At first when I got up in the attic I could see the stains.  It was apparent quickly that there was an issue.

I was a little puzzled at first.  My mind flashed to the possible interaction of the conditioned air in the living space below and the warm humid attic air.  A large opening or bypass?  That seamed unlikely.  Then I turned around.

Uninsulated ducts Randallstown MD

The poor duct was lying completely undressed and quite dirty.


Here is the recipe for mildew and mold growth on the plywood in this attic.

1. 2nd HVAC system located in the attic.  All ductwork servicing upstairs is in the attic.  Ducts are leaky and improperly insulated allowing cold air to escape.

2. 2nd HVAC system improperly sized.  Too large for the space/square footage it is supposed to service pushing cooler air through leaky ducts and into the attic.

leaky ducts maryland attic

3. Thermostat located in a bedroom that is likely subjected to higher temperatures due to the lack of performance of the sytem due to the leakiness/exposure to the hot attic.

4. Poor ventilation in the attic due to improper baffle placement and insulation covering the open areas.  In other words, it looks right, but it is not.

Incorrect baffle installation

A baffle is supposed to act as a channel for the open soffit below.  Yet, look what the installation crew did...


covered soffit vent


The soffit opening is covered with "extra" layer.  It is blocking any intake of air.

proper attic ventilation

The Advice: 

Control the humidity and the mold growth disappears.

How do you do that you ask?

1. Remove the insulation around the soffit/eave areas - full perimeter

2. Reposition the baffles properly to accept the now open air intake areas and in preparation for future added insulation (if applicable). 

       2a. Adding intake can also be a function of a siding project and is advisable if siding is on the list of things to get done.

3. Re-position the insulation to not cover the openings.

4. Seal the duct seams and tightly insulate the supply plenum (main AC duct) to eliminate leakage (lost energy) into the attic.

Breaking Down a BGE Energy Audit
Thursday, August 13 2020

Often times homeowners don't know what a BGE energy audit is or how it can actually help.

For starters, a BGE energy audit can help you avoid choosing the wrong solution to a problem. An energy audit through BGE is a good place to start a home improvement priority list. 

Take the important step of scheduling your BGE energy audit as soon as you can!

Anyone ever get a
Saturday, August 08 2020

I have been on so many home energy audits where the customer's reason for having the audit done is because they keep getting the letter from BGE saying that they are using more energy than their neighbors.  They don't understand why this keeps happening to them.  They swear that they turn off lights, set the thermostat right and they have new windows and doors.

There are two things going on here that need to be addressed.

1. BGE Home Energy Report Program

We all get them.  We all stopped looking at them.  But, every once in a while it pops up in an email and you see the score.  It's never good.  You ask yourself - what else can I do?  You are energy conscious.  You are just living your best life.

Here is the thing about the Energy Report Program.  That is exactly what it is - a program.  There is an element of psychology.  Nobody wants to get beat by their neighbor and they know that.  And, it works.  It moves the needle.  People turn off more lights, upgrade appliances to ENERGY STAR and set thermostats up or down a notch or two.  It saves energy so it works.

Everyone always wants to know if there is any validity to the report and the answer is yes.  Although some information gets left out such as how many people live in the home and what are their daily habits (retired vs. work all day) the report is going to give you a small window into where you stand when it comes to energy usage compared to others.

2. The Value of a Comprehensive Home Energy Audit  

To make a house energy efficient you've got to get a handle on air leakage and most people are not thinking in this way other than windows and doors.

Uncontrolled air leakage occurs when air moves through gaps or openings in walls, floors, ceilings, duct work, doors or windows and is often a major source of energy loss in homes.

When I evaluate a home energy audit report, the story becomes much clearer in terms of where we must look to be more efficient and it is not because lights are on too much.  Additionally, windows and doors account for very little overall leakage when tested.

BGE Home Energy Report

Looking at this sample energy usage report from a comprehensive audit one interesting thing to understand is the green part of the graph.  Notice that the baseload is $50/ mo.  That is the category for lights, computers, fridge, etc.  Clearly the focus needs to be on heating and cooling costs. 

This might surprise you, but replacing HVAC is not the way to make an impact. When considering this provocative statement, go back to the uncontrolled leakage definition and notice all of the areas a house can leak.  Most people only think about the obvious ones. 

Here is the thing: You can put the world's best HVAC system into a leaky house and get zero results.  

Get an energy audit and learn about the ways in which you can passively save energy and money and live in a more comfortable home.  It makes a lot of sense and having an auditor walk you through to learn more about your house is empowering.  It will set you on the best path to save energy in places you might not have thought about otherwise. 

Let us know how you are doing on your BGE energy report.


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Having your home evaluated by Hometrust is a great way to identify your next home improvement project. 
Certifications earned through the Building Performance Institute demonstrate our ability to:

  • Find air leakage points around your home. 
  • Show you steps to improve energy efficiency.
  • Use science to guide improvements to comfort.  
  • Educate you how to tighten your building's shell. 
  • Learn about these opportunties before it is too late. 
  • Provide a unique perspective on your home's overall performance. 
  • Determine the root cause of any problems.
  • Assess current insulation effectiveness.
  • Measure air flow.
  • Evaluate windows, doors, siding and roofing.
  • Put you in complete control of the outcome.
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    Hometrust Remodeling is a licensed contractor specializing in a whole-house approach to home remodeling with an emphasis on educating our customers, providing energy efficient solutions, maintaining a network of high caliber technicians and using building science principles.  As a result, we can effectively guide Maryland homeowners towards projects that satisfy comfort needs, aesthetics and value.

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