passive house and passive solar: a comparison of two approaches to
TRANSCRIPT
Passive House and Passive Solar: A Comparison of Two Approaches to Low Energy Heating
14 May 2012
World Renewable Energy Forum
The Built Environment
Matt Hogan & Alison Kwok
University of Oregon
Passive Solar
“south-facing glass... for solar collection, and thermal
mass for heat absorption, storage and distribution.”
- Ed Mazria
Balcomb House, 1979
Source: nmsea.org
Passive House
“Superinsulation proponents sought to create a simpler
solution with small window areas, large quantities of
insulation, and simple geometries.”
- Alex Wilson, Building Green, Inc.
Saskatchewan Conservation House, 1977
Source: greenbuidlingadvisor.com
Two Approaches Compared
Passive House Passive Solar
Superinsulated Well-insulated
Airtight Not necessarily airtight
Small glazing area Large south glazing area
No significant thermal mass Significant thermal mass
Heat recovery ventilator HRV optional
Compact shape Elongated east-west axis
Constant temperature (68°F) Daily temperature swings
The Learning House
Research Questions
1. Can a passive solar house in Eugene, Oregon maintain an
average indoor temperature of 68°F (20°C) during the winter
design week while using less energy than a Passive House of
an identical program, living area, and volume?
Research Questions
1. Can a passive solar house in Eugene, Oregon maintain an
average indoor temperature of 68°F (20°C) during the winter
design week while using less energy than a Passive House of
an identical program, living area, and volume?
2. Can the indoor temperature swings of the passive solar house
during the winter design week be kept to less than 10°F
above and below 68°F (20°C)?
Methodology
1. Model Learning House in PHPP
Methodology
1. Model Learning House in PHPP
2. Model Learning House in DesignBuilder
Methodology
1. Model Learning House in PHPP
2. Model Learning House in DesignBuilder
3. Redesign Learning House for passive solar
Methodology
1. Model Learning House in PHPP
2. Model Learning House in DesignBuilder
3. Redesign Learning House for passive solar
4. Model passive solar house in DesignBuilder
Methodology
1. Model Learning House in PHPP
2. Model Learning House in DesignBuilder
3. Redesign Learning House for passive solar
4. Model passive solar house in DesignBuilder
5. Compare results of DesignBuilder simulations
Methodology
Variables
- Area of south facing glass
- Thermal mass
- Indoor temperature
Methodology
Variables
- Area of south facing glass
- Thermal mass
- Indoor temperature
Constants
- Assembly R-values
- Backup electric resistance heat
Passive House Model
Annual site electricity use:
10.9 kBtu/ft2yr
Annual CO2 Emissions:
6336.30 lbs
Redesign Learning House for Passive Solar
Area of south glass:
9% of floor area
Solar Savings Fraction: 32%
No significant thermal mass
Passive House
Redesign Learning House for Passive Solar
Area of south glass:
9% of floor area
Solar Savings Fraction: 32%
No significant thermal mass
Area of south glass:
19% of floor area
Solar Savings Fraction: 50%
Mass to glass ratio: 3.7
Passive House
Passive Solar
Area of Thermal Mass
Passive Solar Model
Annual site electricity use:
9.8 kBtu/ft2yr
Annual CO2 Emissions:
5739.97 lbs
Results Compared
Performance Data Passive House Passive Solar
Annual Electricity
Demand (site)
10.9 kBtu/ft2 yr 9.8 kBtu/ft2 yr
Annual CO2
Emissions
6336.30 lbs 5739.97 lbs
Annual Electric
Lighting Demand
4589.04 kBtu/yr 4498.99 kBtu/yr
Annual Heating
from Solar Gains
6645.37 kBtu/yr 9835.51 kBtu/yr