Papers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015.
The article describes details of a new concept of the passive
house. The passive house is a synonym for energy efficient
house with energy demand for heating QH less than 15
kWh/m2·a and a primary energy demand QPE less than 120
kWh/m2·a. In climates where active cooling is needed, the
space cooling energy demand QC roughly matches the heat
demand requirements above, with a slight additional allowance
for dehumidification. Another requirement is related to airtightness.
Uncontrolled air leakage shall be less than 0,6 of
heated volume per hour at increased and decreased pressure of
50 Pa. Thermal comfort must be met for all living areas during
winter as well as in summer, with not more than 10 % of the
hours in a given year over 25 °C.
This concept at the beginning encountered energy efficiency
potentially even health aspects. Two main drawbacks were dry
air in winter and unknown air quality in terms of CO2 which
could resulted in bad air quality in spite of the mechanical
ventilation system with heat recovery (MVHR). At the passive
house conference in 2008 (Nürnberg, Germany) I presented my
own passive house project, which introduced floor heating only
instead of heating through the ventilation system . Another
improvement was implementation of the MVHR with rotary air-to-air enthalpy wheel which was developed many years ago
but commercially available device with sufficient efficiency
was offered shortly before my project started. This system
prevented fast dehumidification of indoor air in winter. Based
on the developed CO2 measurement unit in our laboratory the
speed of ventilation in the heat recovery system was regulated
in order to maintain fresh air under the limit 1000 ppm of CO2.
After almost 4 years of living in the house and regular
measurements of climate variables (temperature, relative
humidity, CO2), analysis of energy invoices for 4 winter
seasons (2011-2014) with calculated energy consumption proved the economic investment and energy efficiency with
increased living comfort and assured healthy environment in
terms of fresh air.