Chapter 5: Designing for Heating and Cooling 5.1 Organizing the problem a) Fenestration How much is optimum for the building? What should the form of the

Chapter 5: Designing for Heating and Cooling

5.1 Organizing the problema) Fenestration How much is optimum for the building? What should the form of the building be?

internal load dominatedskin load dominated

Daylighting issuesside lighting vs top lightingrole of direct sunlight, solar gain vs. glareseasonal adjustments to daylight openingsdaily daylight controldaylight distribution

Chapter 5: Designing for Heating and Cooling cont’d

5.1 Heating issuescan the sun be used to heat spaces? South wall design.openings to other orientations? U-valuerelationship to daylightinghow to minimize cooling effects of large glass surfaces?how can incoming fresh air be warmed?is there surplus heat in the building that can be used at perimeter?

Cooling issuesWhich strategy… Open the building to breezes or close it to retain coolth?How to keep out direct sunlight?How to allow daylighting in winter without overheating in summer?When can cooling be provided by outside air rather than refrigeration?Can use of refrigeration be confined to off peak times?How can incoming fresh air be cooled?Can the structure of the building be used to absorb daytime heat and

flush it out at night?


5.2 Zoning your buildingbased on function, schedule, orientation fig. 5.3

5.3 Daylighting guidelines (calculations optional)daylight factor def’n: indoor illumination from daylight x 100%

outdoor illuminationFig. 5.4 Design diagrams - one way structure → high windowsTable 5.2 Recommended daylight factorsFig. 5.7 EPUD building


5.4 Passive Solar Heating GuidelinesIncorporates sun collection and storage as part of a building’s

wall, floors or ceilings.“Insulate before you isolate”Principle of whole building heat loss.

Relative to conventional buildings, passively solar-heated buildings usually conserve purchased energy, yet buildings that aim at very high percentages of solar heating can use more total heating energy than is used by buildings with smaller window areas. Designers interested primarily in saving purchased energy may aim at lower solar percentages and more insulation; designers interested in buildings that closely relate to climate and climatic changes may aim at higher solar percentages (and more daylighting) along with higher thermal masses and probably greater ranges of indoor temperature.


5.4 b) Solar Savings Fractiona measure of the solar building’s conservation advantage(not the percentage of solar energy used)

c) Thermal mass (calculations optional)phase change materials

d) Orientationbest within 30˚ of south.figures 5.12 and 5.13

e) Roof ponds not recommended for climates with snow since they require moving insulating panels

f) Active Solar HeatingUses mechanical equipment to collect and store solar energy


5.6 Passive Cooling Guidelines a) Cross ventilation

provides air movement and fresh airindoor temperature will be slightly above outdoor temperaturedifficult to quantify

b) Stack ventilationalso maintains slightly above outdoor air temperature

c) Night Ventilation of Thermal MassMaintains a building at temperatures lower than outside by day and flushes the building with plentiful fresh air by night.Example 5.3 describes how to calculate appropriateness of system with respect to climate


5.6 Passive Cooling Guidelines

d) Evaporative coolingcalculations optional

e) Cool towerspassive approach to evaporative coolingFigure 21

f) Roof Pondscalculations optional

g) Earth Tubesfeasible if trenches already required.


5.9 b) Degree Days def’n

5.10 Passive Solar Heating Performance figure 5.13 Passive Solar Heating Systems compared

a) glazing performancethe issue of nighttime insulation


b) Direct Gain Systems

Problems:possible overheating on sunny winter daysinadequate area of thermal mass

Thermal mass should be widely distributed around the room so that direct sun can strike the mass surface or be reflected onto it as soon as possible upon entering the window.

Figure 3.6


c) SunspacesProblem:Expectation that the sunspace will be a greenhouse.Comfortable temperatures in the main spaces are achieved at the expense of very wide temperature swings in the sunspace.

Wall between sunspace and main space should be vented masonry or contain water containers.All sunspace systems are assumed to have a thermally massive perimeter insulated floor slab on grade.Figure 5.26


d) Trombe Walls

The main advantages of the Trombe wall systems: Thermal stability. The diurnal temperature swings are less than with most other passive systems. They deliver a large portion of their heat by radiation to the space.

The main disadvantages:The loss of view and daylightKeeping the air space clean between the Trombe wall mass wall and the glass.

Vented walls use the stack effect to circulate warm air to the main space. Deliver warm air sooner, but introduce dust into the space behind the glass.Unvented spaces deliver heat quite late and are somewhat less efficient than vented spaces.Figure 5.27


e) Water Walls

Water phobia?

A real water wall is not transparent but opaque. Black selective paint (excellent absorber of short-wave solar radiation, poor emitter of long-wave radiation from the heated black surface) behind double glazed unit.

Leave airspace for water expansion due to temperature, also rust inhibitor.

Figure 5.28


5.11 Calculating heat gain (cooling load)

Be aware of the factors involved in heat gain; calculations optional.roof and walls q = U x A x DEDTglassoutdoor air (infiltration, mechanical ventilation)peoplelightsequipmentlatent heat gain (varies with occupancy)


5.14 Passive cooling calculation proceduresRead through the UK pavilion at the Seville Expo 1992.Look at figures 5.48 5.59

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Chapter 5: Designing for Heating and Cooling 5.1 Organizing the problem a) Fenestration How much is optimum for the building? What should the form of the