Four Rules of ThumbThat Could Lead You AstrayRules of Thumb can point you in the wrong direction. Here’s what you need to know so you don’t get misled.
4 Rules of Thumb That Could Lead You Astray
Why do rules of thumb fail?
• They don't take into account the specifics of the site and building design
• They don't apply equally well to all building types
• They don't help you understand what's important, and can draw attention to the wrong parts of a design
We looked at 4 rules of thumb related to the building envelope, and found that they can often point in the wrong direction.
Rules of Thumb
4 Rules of Thumb That Could Lead You Astray
Rule No. 1: The ideal alignment of buildings is for the longest axis to run East-WestThe rule works with a simple rectangular building. But what happens with more complex geometry and shading from surrounding buildings?
Rule No. 2: Shading Depth
4 Rules of Thumb That Could Lead You Astray
Shading devices are tricky, even for rules of thumb: rules can work well for buildings that are externally loaded, south-aligned, and built to standard specifications.
But what happens if we specify a high performance envelope? Do the standard depths still apply?
Rule No. 3: Glazing Ratios
4 Rules of Thumb That Could Lead You Astray
Glazing ratios are intended to optimize solar heat gain, with different rules for different climate zones.
This is an important consideration … but what is the effect of different glazing types or different shading strategies? Do the rules still work?
Rule No. 4: Natural Ventilation
4 Rules of Thumb That Could Lead You Astray
A standard rule of thumb for natural ventilation states that the ideal operable window area is 5% of the total floor area to be naturally ventilated.
Does this % stay the same for different levels of insulation, shading, and thermal mass? And is it enough to maintain occupant comfort?
4 Rules of Thumb That Could Lead You Astray
What’s the best orientation for this office building in Pittsburgh, PA? Which option minimizes energy use?
Putting Rules of Thumb to the Test
A B C
Download the full white paper to see whether your guess was right!
The Sefaira white paper discusses in detail the four rules of thumb presented here. Follow the link below to discover the many cases where rules of thumb go wrong, and explore ways to put them right again!
Sefaira’s White Paper
Contact [email protected] | www.sefaira.com
4 Rules of Thumb That Could Lead You Astray