Literature Review on Building Envelope, Heating and ... - Beeshive.org

Table 4. Range of R-Values of Insulation Used in Houses in Japan’s Cold
Regions
Equivalent Thickness of
Fibreglass cm (inches)
Approximate
RSI-Value (R-value)
Roof 5 to 30 (2 to 12) 2 to 7 (8 to 50)
Wall 5 to 10 (2 to 4) 2 to 7 (8 to 17)
Floor 5 to 15 (2 to 6) 2 to 7 (8 to 25)
Notes:
R-values are calculated based on fibreglass thickness reported by Yoshino (1991).
The R-value of fiberglass is taken as RSI-0.7 per 25 mm/R-4.2 per inch).
Yoshino (1991) reviewed house problems in the cold climate regions in Japan. Yoshino
noted that as houses became more insulated and airtight, many problems arose.
Indoor air pollution increased in terms of CO 2 concentration, which was more than 1000
ppm in many houses and more than 3000 ppm in some areas. CO 2 concentration was
particularly high in houses with unvented portable kerosene heaters.
A back flow in the chimney of the space heater was caused by negative internal pressure (-30
Pa) that is a result of using a large capacity fan (125 L/s (265 cfm) or more) for kitchen
exhaust. Large capacity fans are mandated by the building code when natural gas is used for
cooking. Yoshino noted that the chimney back-flow problem has become a health concern.
Moisture condenses in unheated rooms due to low air infiltration and the fact that only the
living room was heated in many houses.
As a solution, Yoshino suggested the following design strategies and provided examples.
The heating and ventilation equipment and type of cooking appliance should be selected
according to the air tightness level of a house.
• The building code needs to specify lower ventilation rates (suggested 92 L/s (195
cfm)) when electric appliances are used for cooking.
• Kitchen ventilation should be independent of other ventilated zones, because the
required ventilation air volume is large. Kitchen fan operation affects comfort in the
living room and the bedrooms.
Zero-Energy Sustainable Houses
This section reviews a group of homes loosely called zero-energy homes. These homes
actually have very low energy consumption; they are super-insulated, airtight, and
include green features that minimize the impact of the house construction and operation
on the environment.
The Eagle Lake Healthy House
The Eagle Lake healthy house (CMHC 2001-2003, North Series # 5) was built for the
Eagle Lake First Nation in Northern Ontario in 1997 as a demonstration project for
PERD-079: Task 2 - <strong>Literature</strong> <strong>Review</strong> 60