Homeowners your hands one of the most important documents you can possess before you purchase a home! What every Prefab House or potential homeowner absolutely needs to know and understand is this, you as a homeowner have ALL the responsibility to make sure your new home is going to function and be an energy efficient home.
This document is written for the homeowner to understand the city inspections. This article is not referring to the third party inspection completed by a licensed Professional Home Inspector.
If you are concerned about the energy efficiency for your new home the single most important item that impacts energy usage and monthly energy bills is the size of the home. The energy cost to operate your home is directly related to the size, shape and volume of your home. Home builders today are not supplying potential home buyers with two critical pieces of information you need to understand the energy efficiency of a particular home or if you are comparing the homes from two different home builders.
When an engineer designs and sizes the AC equipment for a building large or small he uses a load calculation method to determine how much heating and air conditioning capacity is needed to serve the new building. The same approach and method is supposed to be used today in new homes built in Texas. The home builders in Texas have been building homes in Texas since 2001 that will not meet the required energy code standard and design guides. The load calculation step is the very beginning and most important step in building a home for energy efficiency but is not being performed by builders today. This is simply because most builders do not pay attention, understand the energy code or understand load calculations.
The other problem or issue is that most homeowners have never heard about it and do not care as well. Most homeowners believe that someone else is taking care of this for them. As I stated earlier in this guide this is simply not true or being done.
Homeowners Have To Take Responsibility
How do homeowners know that one home is more efficient than another? The method used to
understand the efficiency of a home in regards to the heating and air conditioning systems is based on a unit of energy known as a “British Thermal Unit” (BTU). I am not going to get real technical here but I will give you the homeowner the information you need to go home shopping with and it is really very simple.
Three Efficiencies Regarding Home Building
1. Thermal Efficiency- Determined by the home construction methods and materials
used to build the home. It is the most important efficiency in home building.
2. Energy Efficiency – Measured and calculated by the conversion of energy input
(KW/BTU) into useful work output cooling/heating BTUH.
3. Overall Efficiency – Is the combination of both efficiencies above. Thermal Efficiency
has a huge impact on the Energy Efficiency rating and therefore will impact the
overall efficiency of the home.
As a homeowner this is what you need to know. The amount of energy required to heat and cool your home is directly related to the amount of heat gain your home experiences when it is warm outside and how much heat loss your home experiences when it is cold outside. This heat gain and heat loss is measured in BTUS. The amount of heat gain and heat loss is measured and defined on an hourly basis so the measurement is in BTUH.
This stands for British Thermal Units per Hour. The higher the thermal efficiency of the home the lower the energy use is. As a homeowner you will receive a better return on investment for each dollar you spend to make your new home more thermally efficient than to build a very poor thermally efficient home and try to make up the overall efficiency with very expensive high end heating and air conditioning equipment. This approach simply does not work over the life of the home.
As a homeowner you have another measurement or consideration to think about and that is the “Return on Investment” (ROI) for your money. If you to take short cuts on the home construction side and purchase very expensive high end AC equipment to make up you may cost your self a lot more money over the life of with expensive repair bills. The cost to repair the high end AC systems is very expensive.
Below is a simple but real example.
– 14 SEER AC System – Replace a failed indoor fan motor. Cost= $250.00
– 20 SEER AC System – Replace a failed indoor fan motor. Cost= $1200.00
The newer systems are very complicated with a lot of electronic components that are very susceptible to power problems and lightning strikes during storms. As a homeowner you need to consider this when building a new home with the least cost to maintain and operate. Homeowners need to spend their money making their home more thermally efficient and use AC system(s) rated at 14-15 SEER instead of 20 SEER systems.
The Questions a Homeowner Needs to Ask a Home Builder
– Mr. Home builder what is the heat gain for this home on July 15th at 3:00 PM in the afternoon?
After he regains his thoughts he will probably reply with; what do you mean? This will give you a real clue here. He does not know anything about the thermal efficiency for the homes he is building!
“You might want to consider a new home builder at this point!”
– Mr. Home builder what is the heat loss for this home on January 15th at 3:00 AM in the morning?
These are the questions that any potential home buyer should ask if they are concerned about energy efficiency and the monthly energy bill for their home. If you are a homeowner who operates on a monthly budget then energy efficiency is very important for your new home. Let us use the example below to demonstrate how the real energy efficiency of two homes should be compared.
– Home A- single story with 2500 square feet of air conditioned living area, all electric home, all energy star rated appliances, and all the lighting fixtures are compact fluorescent and the high efficiency type. The home has a 5 ton 14 SEER rated AC system.
– The heat gain for the home in July is 49,500 Btuh.
– The heat loss for the home in January is 72,000Btuh.
– Home B- single story with 2700 square feet of air conditioned living area, all electric home, all energy star rated appliances, and all the lighting fixtures are compact fluorescent and the high efficiency type. The home has a 4 ton 13 SEER rated AC system.
– The heat gain for the home in July is 44,000 Btuh.
– The heat loss for the home in January is 66,000 Btuh.
Which home is more efficient? Many homeowners would choose Home A simply because it has the largest AC system and highest SEER rating of the two homes. The most efficient home is Home B. This home is larger and is being served with the smallest AC system. Even with the lower SEER rating for the AC system the system is rated at 4 tons and is able to cool the home adequately. The difference in heat gain and heat loss values is what makes home B the most thermally energy efficient.
The size of the AC system does not make a home more thermally efficient. The AC systems in homes are sized to meet the heat gain and heat loss values of the home. The lower the heat gain/loss number the higher the “Thermal Efficiency” is for the home. What makes the home more thermally efficient is size, construction, direction the home faces, window type, wall construction and insulation values to name a few.
The thermal energy efficiency of the home is determined by the construction methods and materials not the heating and air conditioning equipment. The AC equipment only makes a difference in the conversion of electrical energy or the conversion of fuel into useful work- cooling output (Btuh) or heating output. When the SEER rating is higher the conversion of electrical energy is more efficient and therefore the energy bills are lower for the home. A home that only requires a 3 ton AC system to meet the cooling load will be less efficient if the same home has a 5 ton system installed no matter what the SEER value is.
