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Buildings and Their Systems

1. 1. 9. Radiant Barrier Principles and Installations

When talking about good old radiant barriers it is important to keep in mind bigger picture items. 

1. Heat is transferred three ways - conduction, convection and radiation.  Guess which one a radiant barrier affects?... it's radiation, that's why it does work.  Conduction and convection heat gain is slowed down by insulation.
2. How much heat gain comes from the attic (where radiant barrier is typically install)?  Where I live in Phoenix, our attics get super hot, up to 140 degrees in the summer BUT we our homes only get AT MOST 12% of their heat gain from the attics.  So how can a radiant barrier save 30% off a homeowner's utility bill? It's impossible.

That being said, I've seen way too many roofers and sales people promising the world from radiant barrier.  Don't be that guy or gal and find something to sell that is actually going to help someone.

Radiant barriers have low emissivity (lower is better) and high reflectivity (higher is better).

Radiant barriers should not be installed on the attic floor because once a layer of dust covers the radiant barrier, they no longer work.  Radiant barriers should only be installed along the slope of the roof trusses, with at least 1" of clearance between the plywood and the barrier for it to breath.


According to the Department of Energy (DOE), a product classified as a “radiant barrier” must have a high reflectance of at least 90% and a low emittance of 10% or less.  Radiant barrier paints, do not meet that criteria with a reflectance of only 75%.

Next Section

2a. Building Components

1. Identify basic duct configurations and components
   
2. Identify basic hydronic distribution configurations and components
3. Identify basic structural components of residential construction 
   
4. Thermal boundaries and insulation applications 
   
5. Basic electrical components and safety considerations 
   
6. Basic fuel delivery systems and safety considerations
   
7. Basic bulk water management components (drainage plumbing gutters sumps etc) 
   
8. Vapor barriers/retarders 
   
9. Radiant barrier principles and installations 
   
10. Understand fenestration types and efficiencies 
    
11. Understand issues involved with basements, crawlspaces, slabs, attics, attached garages, interstitial cavities, and bypasses 
12. Understand issues involved with ventilation equipment 
13. Understand basic heating / cooling equipment components controls and operation 
    
14. Understand basic DHW equipment components controls and operation 
    
15. Identify common mechanical safety controls 
    
16. Identify insulation types and R-Values 
    
17. Understand various mechanical ventilation equipment and strategies: spot, ERV, HRV 
    

2b. Conservation Strategies

1. Appropriate insulation applications and installation based on existing conditions 
   
2. Opportunity for ENERGY STAR lighting and appliances 
   
3. Identify duct sealing opportunities and applications 
   
4. Understand importance of air leakage control and remediation procedures 
   
5. Blower door-guided air sealing techniques 
   
6. Water conservation devices and strategies 
   
7. Domestic Hot Water (DHW) conservation strategies 
   
8. Heating & cooling efficiency applications 
   
9. Proper use of modeling to determine heating and cooling equipment sizing and appropriate energy use
   
10. Understand the use of utility history analysis in conservation strategies 
    
11. Appropriate applications for sealed crawlspaces basements and attics 
    
12. Identify/understand high density cellulose 
    
13. Appropriate applications for fenestration upgrades including modification or replacement 
    

2c. Comprehensive Building Assessment Process

1. Determine areas of customer complaints/concerns in interview
   
2. Understand / recognize need for conducting appropriate diagnostic procedures including when to refer to a specialist for further investigation
   
3. Interaction between mechanical systems, envelope systems and occupant behavior
   

2d. Design considerations

1. Appropriate insulation applications based on existing conditions
2. Understand fire codes as necessary to apply home performance in a code-approved manner.
3. Understand/recognize building locations where opportunities for retrofit materials and processes are needed to correct problems and/or enhance performance
   
4. Understand climate specific concerns
   
5. Understand indoor environment considerations for the environmentally sensitive
   
6. Understand impact of building orientation, landscape drainage, and grading
   
7. Opportunity potential renewable energy applications: geothermal , photovoltaic, wind
   
8. Understand impact of shading on heating / cooling loads
   
9. Awareness for solar gain reduction in cooling climate/solar gain opportunities in heating climates
   
10. Understand need for modeling various options for heating, cooling and DHW applications, as well as other efficiency upgrades