PASSIVE HEATING STRATEGIES. Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 1. Natural Solar

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1 PASSIVE HEATING STRATEGIES Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 1 Natural Solar Nature does not rely on fragile pumps, & fans, arrays of gauges & dials, or elaborate tracking collectors to run her vast network. Man s systems are generally complicated, inefficient, expensive, & quite fallible Nature seldom is! An Opinion from: David Wright: Natural Solar Architecture Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 2 1

2 A Passive System (as a reminder) Uses no purchased energy Has system components that perform multiple tasks (structural, aesthetic, visual, thermal, ) Is highly integrated into the overall building fabric (inseparably integrated?) Is likely designed as an architectural system by an architect Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 3 Passive System Implications Uses no purchased energy That leaves solar radiation for heating (wind, firewood, biomass might be possible, but their implementation tends to violate the conditions below) System components perform multiple tasks Design solutions must be multi-faceted, such as south glazing that appropriately provides for views, daylight, direct solar radiation, fire egress, aesthetics all without excessive compromise Highly integrated into the overall building fabric Design solutions must be well-thought-out, such as a concrete floor that acts as structure, walking surface, architectural finish, and thermal storage (re-dos on bad decisions are really expensive) Most likely designed as an architectural system Such as the entire south-facing building zone (responsibility for this much of a building is not likely to be turned over to a consultant) Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 4 2

3 Why Value Passive Systems? The energy source is renewable and free, thus: Carbon-mitigation is an important benefit Reduced operating costs (utility bills) are a benefit Energy security (personal and national) is a benefit Reserving fossil fuels for better uses is a benefit Passive systems can substantially contribute to green building solutions (beyond just collecting credits) These systems are architectural The architect can design an integrated solution (with numerous opportunities for design richness, elegance, and creativity) Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 5 Solar Radiation as Heat Source Solar is the logical and most readily available heat source for passive heating systems Measured in Btu/hr sq ft (W/sq m) Statistically predictable under clear conditions Then again, rather unpredictable from day-today considering actual weather occurrences The usable magnitude of this heat source is a function of site latitude, month, time of day, aperture orientation, aperture tilt, and weather Magnitude is generally symmetrical about solar noon (with some site-specific influences, such as morning fog, evening dust, ) Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 6 3

4 Solar Radiation Patterns In general, on a daily basis, the maximum amount of solar radiation will be collected from a south-facing surface (versus east- or west-facing). South is solar south. Some deviation from a true south orientation is often intentionally incorporated to shift collection to the morning or afternoon as a means of better matching building loads to the solar heat source Forced adjustments from south (due, for example, to site conditions) will have predictable consequences In winter, the maximum amount of daily solar radiation will be collected from an aperture that is normal to the sun s rays in the real world, however, such a tilt is often compromised to a vertical surface (because vertical glazing is easily constructed, easily cleaned, and easily shaded for overheated-period control) Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 7 Heating A system or approach intended to increase the temperature of something such as the air in a building. Typically only sensible heating is explicitly addressed in building design. Heating is the opposite of cooling heating requires a heat source. Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 8 4

5 System A specific set of components arranged in a particular way to achieve a defined objective. This definition is especially important to the design of passive systems as the same components rearranged or altered to accommodate other demands may produce different (and possibly conflicting) outcomes design intent and criteria will help define what constitute appropriate arrangements Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 9 Heating System Components Heat source A means of heat distribution (building scale) A means of heat delivery (room scale) Controls <<<<< a passive system has the same conceptual components as an active system >>>>> Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 10 5

6 Heating System Components ACTIVE heating systems: Heat source [many] Heat storage (rarely) Heat distribution Pipes, ducts Heat delivery Diffusers, radiators, Controls Usually automatic PASSIVE heating systems: Heat source [SUN] Heat storage (VITAL) Heat distribution Convection, radiation, etc. Heat delivery Convection, etc. Controls Usually architectural/people Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 11 Passive Heating System Classifications Heat loss reduction <<< START HERE! Direct gain Solar radiation enters occupied space Indirect gain There is a buffer between solar and space Isolated gain There is separation between solar and space Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 12 meets need for heat reduces need for heat 6

7 Heat Loss Reduction Systems These systems produce no heat, but reduce the need for heat (this vital role is expressed in the saying insulate before you insolate ) These systems represent the first move in all successful passive (and active) heating solutions The strategies that constitute these systems involve reducing building heat losses (as expressed though design heat loss) Insulation, air tightness, microclimate modification, comfort zone adjustment, and similar design moves are some of these many strategies Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 13 Direct Gain Systems Basically consists of south-facing glazing with associated heat storage (thermal mass) The simplest system type The cheapest passive heating system The hardest to control Privacy may be an issue (since access to solar radiation also provides visual access) Nighttime switching of aperture is often desirable (to change it from a connector to a barrier) Distribution of heat to non-south spaces is a design issue Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 14 7

8 Direct Gain Basics: Face the sun Accept the radiation Absorb the radiation Store the heat Hang on to the heat Distribute the heat Refinements: Glare control Privacy Appropriateness Aesthetics owner-built project under construction; consider wisdom of having plants Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 15 Indirect Gain Systems Three main indirect gain system variants: Trombe wall (masonry) Water wall (yes, water) Roof pond (also water) The heat storage element acts as a buffer between solar and occupants More complex and more expensive than direct gain systems More control options, thus more privacy Heat distribution to other spaces is an issue Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 16 8

9 Indirect Gain Trombe Wall multi-family housing; consider complexity of providing operable windows Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 17 Indirect Gain Water Wall uses recycled materials; and may be making an intriguing political statement Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 18 9

10 Indirect Gain Roof Pond involves water in containers located on the roof (think about aperture tilt) Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 19 Isolated Gain Systems Sunspaces and similar configurations (these are not true greenhouses for plants) The heat collection function is fully disengaged from the occupied space therefore heat distribution is a major design issue More complex, more expensive than direct or indirect gain systems More control options, thus more privacy Various options for the dividing wall (insulated, thermal mass, vented) Nighttime heat loss from sunspace is a concern Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 20 10

11 Isolated Gain Sunspace Balcomb House, Santa Fe; the house enfolds the sunspace Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 21 Basic Components of a Passive Solar Heating System Aperture (admits shortwave [sw] radiation) Absorber (converts sw radiation to heat) Storage of heat Heat distribution Heat delivery Isolation element (blocks lw radiation & convection) Controls An opening with glazing (defines system size ) Masonry floor or wall surface (or water)1 Floor/wall/ceiling mass Large-scale flow patterns Smaller-scale patterns Glazing Occupant manipulations; architectural elements Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 22 11

12 Passive Solar Heating in Practice no on-off switch, no thermostat, just physics (or building science) Where are: source, distribution, delivery, controls? What type of system is this? Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 23 Band of Sun (a la John Reynolds) maximize exposure to and use of solar radiation when it is beneficial to do so Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 24 12

13 unnamed restroom, in unnamed building, by unnamed architect Sometimes.. You Just Have to Wonder artificial wetland as retention pond, Sainsbury s, Greenwich, UK Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 25 While We Are Looking at Sainsbury s store first in Europe to pioneer green energy system where customers create 30kWh by driving over plates in car park Ball State Architecture ENVIRONMENTAL SYSTEMS 1 Grondzik 26 13