It's Not the Heat, It's the Humidity

My wife declares that she is burning up!

She is fanning herself with a magazine and obviously uncomfortable. However, the thermostat on the wall tells me that the temperature is the same as always for this time of the evening. The T-stat is programmable and the settings haven't been changed. How can she possibly be so hot?

To console her I drop the temperature two degrees, only to be shaking my head 20 minutes later when I see she has covered herself with a small blanket. My initial assumption is that her personal thermostat is broken.

There are some additional details that you need to know. It's early October here in Florida and the outdoor temperature is cooler than the peak of summer. Additionally, rain this afternoon cooled off the roof and inside the temperature is within our comfort range, without the use of air-conditioning. Here's what happened:

1. The AC system has not been running because of the pleasant temperature this time of year.
2. Humidity inside has slowly increased as a result of cooking, showers, laundry and even our breathing.
3. Increased humidity in the air prevents moisture on our skin from evaporating.
4. Comfort comes from a combination of temperature, humidity and air movement.

Camie was uncomfortable because the increased humidity prevented evaporation from her skin. When I turned on the AC, in addition to dropping the temperature two degrees it also removed the excess humidity in the room and created a draft. Admittedly, her personal T-stat is a bit more sensitive than mine, but she had just experienced a drastic change in all three of the components that affect comfort.

The Southern Home may need additional dehumidification during times of the year that pleasant temperatures prevent your AC system from operating. I wrote another article recently on the subject titled, All Southern Homes Need Dehumidification. Since running the AC is costly, a separate dehumidifier is worth considering to increase comfort during periods of Spring and Fall when temperatures are pleasant.

Dog Trot

Long before air-conditioning was invented, homes throughout the southeastern United States were designed to capture cooling breezes and shade their occupants from the hot southern sun. The Dog Trot is a design that was common during the 19th and 20th centuries, that was used with various architectural and regional styles.


The plan consisted of two enclosures connected under one roof and separated by a breezeway. Typically one enclosure would be used for cooking and dining, and the other used for living and sleeping spaces. The separation kept the heat of the kitchen out of the remainder of the house. 

The additional benefit of the breezeway was its ability to capture breezes and actually increase the velocity of air movement. With the help of deep overhangs or front and rear porches, even the lightest breeze was captured and funneled between the two enclosures. By opening doors and windows to the breezeway, and windows on the far side of the enclosures, cross-drafts were created that removed heat and made the living spaces more comfortable.

Modern home designs can benefit from lessons of the past. As energy costs continue to rise, it makes sense to look back at the techniques that were used to remove heat and improve comfort in our homes. Zoned living spaces, large overhangs, covered porches and cross-ventilation can all contribute to the architectural style and performance of the Southern Home.

courtesy of Dan Gregory, Architect

All Southern Homes Need Dehumidification

Ventilation and Dehumidification are critical talking points, especially here in Florida. Until recently they were discussed little, but the way we build homes is changing and they are now important issues.

A well-insulated home will maintain its temperature during moderate times of the year. As a result, the air-conditioning system will not operate very much. Typical thermostats only measure air temperature, but humidity, air movement and air quality all affect our comfort. Cooking, showers, and even breathing raise the humidity level in the home.
               
When the humidity level is too high, moisture ceases to evaporate from our skin making us feel clammy and sticky. Even light breezes lose their refreshing feel. High humidity levels support the growth of mold and mildew, and allow the air we breath to carry more impurities not present at lower levels.

Here in Florida during the spring and fall, without the use of air-conditioning, humidity levels will rise in the home causing uncomfortable and potentially even unhealthy conditions. Efficient dehumidification without the added expense of operating the AC or heating system, is the answer to lowering humidity levels and increasing comfort. We have several interesting articles available for view in our Building Science collection if you want to learn more.

To summarize: more insulation + tighter construction = less AC & more humidity. In an upcoming article I’ll discuss ventilation and its role in the southern home.

Behavior and Habits

As a new empty-nester couple, our power and water (and grocery) bills have dropped substantially now that our kids have moved out of the house. I learned conservation from my father, who wouldn’t turn on the AC until he saw beads of sweat running down your forehead. While I’m not quite that extreme, I do take a “military shower”, as Dad referred to it. I turn the shower on to get wet, then turn it off to lather up, and then turn it back on to rinse. My shower water usage doesn’t exceed a minute; a fraction of time compared to our now absentee family members.

Behavior and attitude may have the most impact on our energy and water use.  While my habits help me save, there are some strategies to consider when building a new home that can help you conserve too.

• Solar orientation, natural lighting and shading, take advantage of the seasonal arch of the sun, to provide light and heat when it’s wanted, and prevent excess heat gain when it’s not.
• Zoning and programmable thermostats allow you to control the AC and heating in the areas of the house where you spend your time, effectively reducing the amount of living space that has to be conditioned.
• Stand-alone dehumidification increases comfort at a set temperature without running the AC.  The saying, “It’s not the heat, it’s the humidity”, was probably coined here in central Florida.
• Lighting design and control can reduce the number and length of time electric lighting is needed, but still maintain security and convenience.
• Operable windows can be oriented to catch breezes and exhaust heat, while still providing security and allowing use during rainy weather.
• Native Florida landscaping that has adapted to the environment, requires less water and maintenance while adding to the beauty of the property.
• A convenient location to line-dry clean laundry saves energy used by the dryer and extends the life of clothing and linens, all while adding a crisp, clean feel.

These are a some of the ideas that can greatly reduce energy and water use, plus there are also many other ways to reduce demand and increase efficiency with the design and construction of a new home.  Look for more posts on these subjects soon.  Keith Groninger

Has the term "Green" been Over-Utilized?

I’ve occasionally observed confusion and resistance surrounding conversations about green construction and lifestyles. I wonder why some people stumble while others are jumping on the green bandwagon, so I’ve decided to remove “green” from the discussion. Here’s a list that I compiled of potential benefits related to the design, product selection and construction techniques that might be considered when planning a new home or renovation project:

• Community Impact
• Durable Construction
• Energy Efficiency
• Environmental Awareness
• Health and Comfort
• Operations and Maintenance
• Property Characteristics
• Resource Utilization
• Site Development
• Waste Management
• Water Conservation

What factors do you use in the decision-making process?