Locate garages or storage areas on the side of the
building facing the coldest wind to help insulate
Storage/ mechanical/ and bathroom spaces are all
situated towards the southwest side of the residence,
where the prevailing winds are strongest , despite
competing with recommendations to increase
fenestration along the south facade, glazing is kept low
to prevent excessive infiltration
14
15
High Efficiency furnace (at least Energy Star)
should prove cost effective
31
Organize floorplan so winter sun penetrates into daytime use
spaces with specific functions that coincide with solar orientation
Circulation spaces are all oriented along the
northern facade, allowing heat gain during the
winter and maximizing space for cooling ventilation
and a chimney affect to work during the summer
8
Sunny wind-protected outdoor spaces can extend living areas in coolweather
(seasonal sun rooms, enclosed patios, courtyards, or verandahs)
18
Keep the building small (right-sized) because excessive
floor area wastes heating and cooling energy
3
The building is kept long and narrow,
oriented East=to=West, in accordance with
recommendations set forth in
The Passive Solar Energy Book
16
Trees (neither conifer or deciduous) should not be planted in front of passive solar windows, but are OK beyond 45 degrees from each corner
Lower the indoor comfort temperature at night to reduce heating energy
consumption (lower thermostat heating setback) (see comfort low criteria)
Lowered heating temperature from
o
65 F - 68 F when occupied and awake to
o
o
60 F - 63 F when sleeping
o
39
It is proposed that the optimal locations for a whole-house fan
would be above the first-floor living space
A whole-house fan or natural ventilation can store nighttime ‘coolth’ in high
mass interior surfaces (night flushing), to reduce or eliminate air conditioning
1
19
Tiles or slate (even on wood floors) or a stone-faced fireplace
provides enough surface mass to store winter daytime solar
gain and summer nighttime “coolith”
Despite this recommendation, the majority of the glazing area is situated
on the northern facade, minimizing prevalent winds coming from the
southeast. However, the southern-exposed glass was expanded to
increase passive solar lighting along the south of the residence
For passive solar heating face most of the glass area south to maximize
winter sun exposure, but design overhangs to fully shade in summer
Traditional passive homes in cool overcast climates used low mass tightly
63 sealed, well insulated construction to provide rapid heat buildup in morning
While the residence is located in a cooler climate zone, the narrow Eastto-West orientation of the building allows it to maximize rapid heat buildup
throughout the day. This is improved by the inclusion of northern-facing
fenestrations and clerestory windows to allow for more efficient ventilation
Provide double pane high performance glazing (Low-E) on west,
but clear on south for maximum passive solar gain
20 north, and east,
23
Small well-insulated skylights (less than 3% of floor area in clear climates,
5% in overcast) reduce daytime lighting energy and cooling loads
13
The double roof system was designed to work effeciently within
o
the cold climate of Colorado, with a 50 roof facing southward to
o
maximize solar energy collection and a 33 roof facing
north to allow for rainwater collection
The north-facing clerestory windows allow for an increase in passive
heating and daylighting strategies, reducing daytime lighting energy
and cooling loads, particularly within the second story
12
Insulating blinds, heavy draperies, or operable window
shutters will help reduce winter night time heat losses
Steep pitched roof, with a vented attic over a well-insulated ceiling, works
well in cold climates (sheds rain and snow, and helps prevent ice dams)
2
If a basement is used it must be at least 18 inches below frost line and
insulated on the exterior (foam) or on the interior (fiberglass in furred wall)
Insulation/ wall construction recommendations:
11
Heat gain from lights, people, and equipment greatly reduces
heating needs so keep home tight, well insulated
(to lower Balance Point temperature)
4
Extra insulation (super insulation) might prove cost effective,
and will increase occupant comfort by keeping indoor
temperatures more uniform
62
Traditional passive homes in temperate climates used light
weight construction with slab on grade and operable walls
and shaded outdoor spaces
2
If a basement is used it must be at least 18 inches below frost
line and insulated on the exterior (foam) or on the interior
(fiberglass in furred wall)
5
Carefully seal building to minimize infiltration and eliminate
drafts, especially in windy sites
(house wrap, weather stripping, tight windows)
22
Super tight buildings need a fan powered HRV or ERV
(Heat or Energy/ Recovery Ventilator) to ensure indoor air
quality while conserving energy
Average daily temperatures:
Occupied/awake: 76-80 cooling/65-68 heating;
Unoccupied: 80-83 cooling/60-63 heating;
Sleeping: 76-80 cooling/60-63 heating.
Calculating Building Balance Point:
Tb=Ti-(Qi/UA)
Where Tb = balance point temperature,
Ti = average indoor temperature over 24 hrs. in winter, = (65+62+63)/3 = 63
R-value of construction assembly (wall, roof, floor, windows, & doors) = 0.399
Qi = rate of internal heat gain (BTUH-sqft), =.399*1500=599
UA = rate of heat loss (BTUH-°F-sqft). =
(0.03+0.019+0.03+0.17+0.15)*1500*(65-40) = 14963
Tb = 63 – (599/14963) = 62.96
Building Balance Point = Approximately 63oF
100o
90o
80o
70o
60o
50o
40o
30o
20o
10o
0o
Sources:
*In accordance with ASHRAE Standard 55 and Current Handbook Fundamentals Model
Colorado State University, “Heating Colorado Homes,” http://www.ext.colostate.edu/pubs/consumer/10636.html
Michael Utzinger & James H. Wasley, “Vital Signs: Building Balance Point,” Johnson Controls Institute for Quality in Architecture, University of Wisconsin-Milwukee, http://vitalsigns.ced.
berkeley.edu/res/downloads/rp/balance_point_balance_point_big.pdf
Texas A&M University, “Annual Energy Use Calculations,” http://tamu.edu/faculty/choudhury/note16.html
Sensible House, “How to Design & Build Deep Green Homes on a reasonable budget,” http://www.sensiblehouse.org/nrg_heatloss.htm
Denver Colorado Weather & Denver Climate information, “http://www.denver.org/about-denver/weather/