Re: Passive House - energy efficiency
From: James Kacki (
Date: Tue, 23 Aug 2011 21:46:04 -0700 (PDT)
Reply to Norm's question:
Air exchange is a Code requirement now and it is most often accomplished by an HRV (Heat Recovery Ventilator). Indoor air is blown out through the HRV and outdoor air is sucked in through the HRV. The air is passed through many adjacent fins so that the heat is exchanged for energy efficiency. The best ones are, I believe, about 80% efficient

On 23-Aug-11, at 4:01 PM, Norman Gauss wrote:

How do these tight thermal envelopes solve the problem of indoor air
quality? Unless some fresh air is exchanged for stale indoor air, indoor
air quality is likely to become very unhealthful.

Norm Gauss

-----Original Message-----
From: Fred H Olson [mailto:fholson [at]]
Sent: Tuesday, August 23, 2011 1:04 PM
To: Cohousing-L mailing list
Subject: [C-L]_ Passive House - energy efficiency

In her message "Lancaster update, and ..."
On 19 Aug 2011 Fiona Frank wrote:

Lancaster Cohousing is building 34 passivhaus houses and a common
house at Forge Bank on the banks of the Lune River 3 miles outside of
the small north western UK city of Lancaster

"passivhaus houses" caught my attention since in recent months I have become interested in this very high standard or energy efficiency. In the US the
phrase "passive house" is used widely instead but this term is easily
confused with the term passive solar building design. The two terms are
different.  To further confuse things passive house designs often
incorporate passive solar.

The passive house standard was mentioned briefly on cohousing-L previously
but warrants more coverage.  IMHO any new construction should take the
standard into consideration.

Excerpt from

 The term passive house (Passivhaus in German) refers to the rigorous,
voluntary, Passivhaus standard for energy efficiency in a building,
reducing its ecological footprint.  It results in ultra-low energy
buildings that require little energy for space heating or cooling.

Key to achiving the standard is super insulation and a very carefully and
tightly constructed thermal envelope.

This and other features result in a conventional central heating system is not being necessary. A typical statement is that a passive house can be
heated with the equivalent of a hair dryer.

Passive houses are up to 14% more expensive upfront than conventional
buildings but this is quickly recouped from energy use savings.

Retrofitting a house to meet passive house standardds is possible but much
more difficult than with new construction.

We had a passive house architect evaluate our house and concluded with him
that it is not reasonable to retrofit our house to the standard.


Fred H. Olson  Minneapolis,MN 55411  USA        (near north Mpls)
     Email:        fholson at      612-588-9532
My Link Pg:         My org:
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