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Green Collar Careers - HVAC System & Structural Thermal Efficiency

Recalling from Chart 202 the HVAC system consumes the most power of any of the appliance groups.  Homes built before 1990 tend to be less energy efficient. Doors and windows are certain to have air leaks, as will wall socket plates and more. Significant air leaks can effectively double the load on an HVAC system during extreme weather. For a $300 power bill, that equals about $100. Most door and window seals can be repaired.

Few will have programmable controls for the HVAC systems. If the family is out of the home at work/school 5 days a week, a programmable thermostat system can realistically reduce the HVAC load by 20% - that’s net savings of about 6% of the power bill.

Over the last decade HVAC systems have been built with major improvements in efficiency and are given a Seasonal Energy Efficiency Rating (SEER). The simple explanation is the power consumption ratio between a SEER 10 and SEER 18 is 10/18 meaning the SEER 18 will require 55% of the energy of the SEER 10 to perform the same cooling.  Customers will be reluctant to spend thousands of dollars to upgrade their HVAC systems.  However, the lower the SEER number, the more you'll be able to save them with the simple steps below.

HVAC System Maintenance
Unless the mechanicals have been recently updated, the HVAC systems will be less efficient systems and are likely overdue for a coil cleaning at the least. The air handler should draw air in through a filter. Clogged filters restrict the airflow making the compressor work much harder. The more dust that does get through the air handler, the more that clings on the evaporator coil, effectively insulating the core from the air. Dirty evaporator coils can easily drop the efficiency of an HVAC by 5%, effectively adding 1.5% to the monthly power bill.

Likewise on the outdoor condenser coils, build up of grass clippings and dirt will reduce their efficiency. Also some of the foil fins on the coils may be damaged from object rubbing against them like yard tool wheels. Dirty condenser coils can easily drop the efficiency of an HVAC by 5%, effectively adding 1.5% to the monthly power bill.

Most evaporator and and condenser coils are easy units to service with a small and powerful shopvac and a few 1/4" nutdrivers/screwdrivers to gain access.  95% of all the "AC Tuneup" specials the AC service companies charge $90 for are nothing but cleaning the coils.  A good technician can finish the job in 15 minutes.  This is a very worthwhile action to add to your Home Energy Audit service.  To learn more about door seals and repairs use the search tool below to look up AC condenser coil cleaning.
 

Air Leaks Doors and Windows
Door leaks around seals are typically the largest air losses in any home.  Typical door weatherstripping replacement materials cost under $20 and take less then 10 minutes to replace.  This may be a service you'll want to add to your business, in which case you'll need an inventory of various seal types.  Most door seals begin to leak after as little as 2 years, and in most cases only have about a 5 year life.  To learn more about door seals and repairs use the search tool below to look up door weatherstripping.

Window leaks are generally more difficult to detect and repair, and usually account for much less leakage then doors.  If a home has evidence of warped window frames, the best solution is to recommend replacement.  Windows that let sunshine in also let heat in.  In southern climates this can add significantly to the load on an air conditioner, while contributing much less of the heat in the winter.  A simple estimate of how much solar heat these windows are adding add up the square footage of the windows and the number hours before and after noon they receive direct sunlight.  Multiply each square-foot * the number of hours (maximum of 6 hours) * 8 Watts to get the number of watt hours per day of heat.  For example a home with 200 square feet of windows for 8 hours a day would equal:

(200 * 6 Hours * 8 Watts) / 1000 =  9.6 kWh per hot summer day!

Adding solar film will reduce the summer heat by 60% or 5.7 kWh per day.  Conversely, on the same home it would add 2.9 kWh in the winter months to an electrically heated home.  Solar Film is a fairly easy product to install and you may want to add it to the list of services you'll perform.  To learn more about solar film and application use the search tool below to look up Solar Film.

Insulation
Insulation provides a barrier between the inside and outside climates however its often overrated for the actual effectiveness.  While attic heat losses are important with winter heating bills, in the summer fiberglass insulation is much less effective due to the infra red heat energy.  Radiant barriers offer a huge improvement and can be relatively easy to install in attics that have access.  Radiant barrier materials generally cost about $0.25 per square foot and take roughly 8 hours to install in a 2000 square foot attic.

A simple estimate of how much solar heat radiant barriers are blocking add up the square footage of the attic space with radiant barriers and the number hours before and after noon they receive direct sunlight.  Multiply each square-foot * the number of hours (maximum of 8 hours) * 4 Watts to get the number of watt hours per day of heat.  For example a home with 2000 square feet of windows for 8 hours a day would equal:

(200 * 8 Hours * 4 Watts) / 1000 =  6.4 kWh per hot summer day!

To learn more about radiant barriers and installation use the search tool below to look up Radiant Barrier.