How we test the physics behind every Aris design.

A lightweight room with south glass. It establishes the basic heat balance (conduction, solar gain, internal gains, thermostat control) before the suite changes one ingredient at a time.

Case 600 rebuilt with heavy thermal mass. The room should bank heat and release it later instead of reacting immediately to every outdoor and solar change.

Case 600 with a south overhang. It isolates exterior shading and asks whether the moving shadow lands where the sun actually is.

Heavy mass plus the south overhang. The shade changes the solar pulse; the mass decides what happens to the heat that remains.

The glass moves from south to east and west. Morning and afternoon gains should arrive on time, making orientation and hourly solar geometry do the work.

Heavy construction with east/west glass. Solar timing and heat storage have to cooperate across the whole day.

East/west windows gain overhangs and side fins. It pushes compound shadow geometry without changing the lightweight room beneath it.

Heavy mass, east/west sun, overhangs, and fins must all compose correctly; no single mechanism gets to hide behind the others.

The heating setpoint drops overnight, then ramps back to 20°C in the morning. With unlimited ideal heat, the case exposes schedule timing and the building's peak heat demand.

A heavy building follows the same overnight setback and morning setpoint ramp. The ideal heat needed to hold that schedule interacts with yesterday's stored heat, making this a subtle coupled test.

A fixed mechanical ventilation flow runs overnight, heating is disabled, and ideal cooling is available only by day. The case isolates airflow, schedule timing, and the resulting sensible cooling load.

The same scheduled mechanical ventilation meets heavy construction. The model must track how the night airflow removes stored heat and changes the next day's ideal cooling load.

Only the window system changes. The result tests whether lower emissivity, gas fill, conductance, and solar optics stay internally consistent.

The deliberately weak window makes film coefficients, glass conductance, and solar transmission much harder to blur together.

A free-floating sunspace shares heat with a conditioned back room. Solar capture, storage, and interzone transfer must cross the common wall at the right time.

The same lightweight room receives much stronger insulation, isolating whether envelope conductance changes by the amount the assemblies promise.

High insulation and high mass work together. The model must separate reduced heat flow from the delayed heat flow caused by storage.

Ideal heating and cooling loads meet at the same 20°C setpoint. It exposes threshold logic and any hidden deadband assumptions.

A zero-deadband ideal-load control holds a massive room at 20°C, testing whether stored heat and the heating/cooling thresholds interact cleanly.

Strong insulation and a zero-deadband thermostat combine two otherwise simple changes and reveal whether their effects compose.

The most buffered basic case combines insulation, mass, and tight thermostat control into one coupled response.

With mechanical heating and cooling removed, the hottest, coldest, and average temperatures reveal whether solar and envelope heat are stored or spike directly into the air.

A free-floating high-mass room should damp temperature swings through real storage, making this a clean test of thermal inertia.

With heating and cooling removed, a fixed mechanical ventilation flow runs overnight. The free-floating temperature exposes airflow timing and passive heat storage directly.

The high-mass room floats while night air can cool it. Storage and ventilation must work together without a thermostat covering their tracks.

With heating and cooling removed and envelope losses suppressed, small errors in gains, solar, and air heat capacity become much easier to see.

High insulation and heavy mass remove most fast responses. Temperature drift should be slow, damped, and physically earned.

Internal gains and infiltration disappear while high-conductance elements dominate, creating a clean baseline for the diagnostic cases around it.

This case isolates longwave radiation among interior surfaces so convective and radiant heat exchange cannot quietly trade places.

Exterior longwave exchange is isolated to test how surfaces radiate toward the sky and surroundings.

Interior and exterior longwave mechanisms run together, checking that two individually sound radiation models still conserve energy when composed.

Windows and special conductors are removed so opaque-envelope conduction has nowhere to hide.

Add infiltration to the stripped-down base case and observe the load it creates without other mechanisms muddying the result.

A controlled internal gain tests how heat is split, stored, and delivered to the zone.

Changing exterior absorptance isolates sol-air response on opaque surfaces without changing their underlying conductance.

South glass is introduced into a deliberately simple room so transmitted solar can be measured with minimal interference.

The interior's reflectance changes, testing whether admitted solar is distributed, reflected, absorbed, and stored by the right surfaces.

A simple south aperture gains an overhang, separating shadow geometry from the complexity of the full basic building.

East and west apertures test morning and afternoon timing in a room designed to suppress competing signals.

Overhangs and fins shade east/west glass in the simplified diagnostic building, making geometric errors easier to localize.

A heating/cooling deadband is added to the window diagnostic, isolating the effect of control thresholds on solar-driven loads.

This is the deadband-controlled reference point for another family of one-change-at-a-time tests.

Opaque solid conduction is tested again under a heating/cooling deadband to expose interactions with control logic.

Infiltration is added to the deadband base case, showing how air exchange changes both heating and cooling demand.

Controlled internal gains interact with the deadband, testing whether useful heat and cooling penalties appear in the right seasons.

Exterior absorptance changes while thermostat controls remain active, connecting opaque solar heating to annual loads.

Solar gains are removed so thermal storage can be judged from envelope and internal heat flows alone.

Interior reflectance changes under active controls, testing solar redistribution without changing the amount entering the room.

Solar distribution and heavy thermal storage combine, revealing whether the model puts radiant heat into the surfaces that can actually bank it.

Interior and exterior surface coefficients are prescribed constants, turning off dynamic-film differences to expose the remaining heat balance.

Only the interior surface coefficient is prescribed, isolating room-side convection and radiation assumptions.

Only the exterior coefficient is prescribed, isolating wind, convection, and exterior longwave treatment.

This difference cancels much of the shared model and isolates what changing from lightweight to heavyweight construction actually did.

Both cases are heavy. Their difference isolates the response to moving glass from south to east and west.

Subtract the ordinary heavy room from the two-zone sunspace case. What remains is a focused test of interzone coupling and sunspace physics.

Add south glass to a blank high-conductance box. The difference is the purest measure the suite has of how much solar crosses the glazing in the first place.

Interior shortwave absorptance drops from 0.9 to 0.1, so the room stops soaking up sun and starts bouncing it back out. The only isolated test of interior re-loss in the Standard.

Move the windows from south to east and west. The annual totals shift because the gain now arrives morning and evening rather than midday.

A south overhang blocks the high summer sun and lets the low winter sun through. The difference should be nearly all cooling, with heating barely moved.

Overhangs and fins on east and west windows. Harder than shading the south, because the sun these windows see is low in the sky.

Swap a fixed setpoint for a deadband. What the difference isolates is how much of the load was the thermostat chasing small excursions.

Case 395 conducts through solid walls; 400 restores the high-conductance elements. The difference is that element on its own, with the deadband held constant.

Add infiltration to the deadband base case. The two cases are otherwise identical, so the difference is the ventilation path alone.

Internal gains switch on. Heating should fall by roughly what the gains supply, and cooling should rise by the part the building cannot shed.

Interior absorptance again, but under deadband control and against the low-mass base case. A second, independent read on the same interior mechanism.

Exterior solar absorptance rises, so the opaque envelope starts collecting sun. Tests the shortwave path on walls rather than through glass.

Isolates the aperture a second time, in a different cell than 270−220. Two routes to the same physics should agree.

Swap clear double-pane for low-emissivity argon. Cooling should fall sharply and heating should rise as the same coating keeps winter sun out too.

Single pane instead of double. Conduction and solar both increase, and the difference tests whether they scale together correctly.