Small calculations. Better decisions.

Dew point & surface margin

Compare an indoor surface temperature with the estimated dew point.

Assembly heat loss

Compare heat flow through a wall, roof or window area.

Extra insulation thickness

Estimate an ideal continuous layer needed to reach a target U-value.

Ventilation heat loss

Estimate the heating load associated with outdoor-air ventilation and heat recovery.

Insulation heat and energy savings

Screen the annual transmission-heat, purchased-energy and cost reduction from improving one building element.

Air changes to ventilation airflow

Convert floor area, average ceiling height and a chosen air-change rate into continuous airflow.

Ventilation fan electricity

Estimate daily and period electricity use from the measured or rated supply and extract fan power.

Wells & water

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Rainwater collection & overflow

Estimate one rainfall event and the amount a tank can receive.

Household water demand

Estimate daily use and an explicit buffer-storage volume.

Well drawdown & specific capacity

Interpret water levels from a recorded pumping test.

Pump head & electrical power

Combine lift, delivery pressure and friction in a first-pass pump calculation.

Water velocity in a pipe

Convert flow and internal pipe diameter into water velocity.

Water volume in a round tank

Estimate the water held in a vertical cylindrical tank from its internal dimensions.

Water pressure to head

Convert water pressure into metres of head and psi using a stated density.

Hot and cold water mixing

Estimate hot and cold volumes needed to reach a target mixed-water temperature.

Water stored above a well-pump reserve level

Estimate the cylindrical water column and volume above a protected pump-intake level.

Observed well water-level recovery

Convert a measured rise in a cylindrical well into equivalent volume and an average recovery observation.

Rainwater storage balance for a dry period

Compare usable tank water with expected demand and dependable inflow over a chosen period.

Bladder pressure-tank drawdown estimate

Estimate the water delivered between pump cut-out and cut-in pressures from a precharged bladder tank.

Well-pump cycle-rate screening

Estimate one pressure-tank draw-and-refill cycle under a steady water demand below pump capacity.

Well supply and peak-demand buffer

Compare a measured source flow and usable stored water with one defined period of peak household demand.

Water volume inside a pipe

Calculate how many litres a straight pipe run holds from its internal diameter and length.

Tank fill time with simultaneous demand

Estimate how long a tank takes to reach capacity when water is entering and may also be used.

Pressure-tank nominal size from required drawdown

Estimate the nominal bladder-tank volume needed to provide a chosen usable drawdown between switch pressures.

Water lost through a leak

Turn an observed leak flow and daily duration into water volume and an estimated bill impact.

Hot-water wait time and wasted water

Estimate how long cooled water must run before hot water arrives, plus the daily and annual water sent to the drain.

Well specific-capacity and pumping-level screen

Turn one stabilized pumping observation into specific capacity and a cautious linear screen for another flow.

Rainwater first-flush volume

Estimate the initial roof runoff to divert before sending rainwater toward storage.

Gravity-tank water pressure at an outlet

Estimate the pressure available from the lowest tank water level after elevation and entered flow losses.

Independent energy

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Generator running & starting load

Check one documented motor start against other running loads.

Daily electricity budget

Add three appliance groups using power and actual daily running time.

Solar array energy balance

Estimate DC array size from daily energy and a monthly solar assumption.

Battery autonomy

Convert a daily load into nominal battery capacity with stated losses.

Energy to heat water

Estimate heat and input energy for a known water volume and temperature rise.

Shower water, energy and running cost

Estimate water use, water-heating energy and combined operating cost for a household shower pattern.

Battery recharge time

Estimate ideal recharge time between two states of charge.

Generator fuel runtime

Convert usable stored fuel and measured consumption into a simple operating-time estimate.

Solar energy balance over a low-sun period

Compare estimated solar production with critical-load demand over several days.

Generator-assisted battery recharge plan

Estimate recharge time, generator-side demand and fuel for a stated battery deficit.

Battery autonomy after load shedding

Compare battery runtime before and after reducing the daily critical-load budget.

Pump electricity use and operating cost

Estimate electricity and cost from measured input power, daily run time and a chosen period.

Hot-water recirculation energy and cost

Estimate annual pump electricity and the energy needed to replace heat lost from a hot recirculation loop.

Hot-water tank recovery time

Estimate the energy, cost and ideal time needed to heat a stored volume between two temperatures.

Usable hot-water storage

Estimate the mixed-water volume, shower time and stored heat available from a hot-water tank.

Frost & ground

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Pipe cover to trench depth

Convert an established pipe-cover requirement into a trench section.

Heat-trace energy use

Estimate connected load and energy use for a thermostatically controlled heating cable.

Foundation frost-depth screening comparison

Compare a planned bearing depth with a locally established frost-protection target.

Foundation bearing and excavation elevations

Translate final grade, bearing depth and a working layer into site elevations and excavation depth.

Wastewater

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Wastewater hydraulic load

Explore daily wastewater volume and a holding-time scenario.

Gravity drain fall

Convert pipe length and slope into vertical fall and a downstream invert depth.

Wastewater pump outage buffer

Estimate how long the known usable volume in a pump chamber can accept reduced household flow.

Septic solids service interval

Use measured sludge and scum layers to estimate when a chosen service threshold may be reached.

Sump pit storage and pump cycling

Estimate active pit volume, fill time, drain time and starts per hour from measured levels and flows.

Sump pump battery runtime

Estimate outage runtime from usable battery energy, pump duty cycle and standby load.

Water treatment

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Filter-media contact time

Estimate empty-bed contact time and hydraulic surface loading for a cylindrical media vessel.

Filter service-life planner

Turn a rated treated-water capacity into a conservative replacement date estimate.

UV intensity × exposure time

Show the unit relationship between ultraviolet intensity, exposure time and nominal dose.

Water-softener regeneration and salt estimate

Relate hardness load, daily treated volume and usable exchange capacity to an estimated regeneration interval.

Filter backwash flow and water use

Check the backwash flow required by a cylindrical media vessel against the water supply available at the filter.

Construction

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Concrete volume and order allowance

Calculate geometric concrete volume and a separate ordering allowance.

Trench excavation volume

Estimate in-place and loosened spoil volumes for a straight trapezoidal excavation.

Roof runoff peak flow

Estimate peak roof runoff from connected area, rainfall intensity and a runoff factor.

Pipe bedding and surround material volume

Estimate separate bedding and pipe-surround volumes for one uniform trench segment, including pipe displacement and an order allowance.

Masonry unit quantity

Estimate blocks or bricks from net wall area, unit face size, joint thickness and an explicit allowance.

Floor screed volume and bag estimate

Convert measured floor area and average screed thickness into volume and bags using the product’s declared yield.

Paint quantity and can estimate

Convert measured paintable area, coats and the product’s declared coverage into litres and whole cans.

Tile quantity and pack estimate

Estimate full tiles, order area and packs from the net surface, tile dimensions and a stated cutting allowance.

Roof pitch and slope length

Convert a measured rise and horizontal run into pitch angle, slope percentage and sloping length.

Roof covering area and pack estimate

Convert a simple horizontal roof footprint and pitch into sloping area, order area and whole packs.

Roof outlet and downpipe count

Convert roof catchment and design rainfall into a preliminary number of rated outlets or downpipes.

Gutter fall and support set-out

Turn gutter length, intended fall and maximum support spacing into end level and evenly spaced support points.

Flooring area and pack quantity

Estimate net floor area, layout allowance and whole packs from effective pack coverage.

Wallpaper area and roll quantity

Estimate wall area and whole rolls using the product’s effective coverage after pattern matching.

Plaster mix and bag quantity

Estimate dry plaster mix from finished area, average thickness, product consumption and allowance.

Drywall sheet quantity

Estimate whole boards from net lined area, sheet size and a layout-specific allowance.

Electrical power

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DC cable voltage drop

Estimate copper-cable voltage drop, percentage loss and heat at a steady current.

Inverter DC input current

Convert an AC load and inverter efficiency into approximate battery-side power and current.

Battery runtime from a steady load

Estimate ideal runtime from nominal energy, usable fraction, inverter efficiency and load.

Inverter running and motor-start screen

Compare one documented motor start plus other loads with derated continuous and surge inverter ratings.

DC cable area for a voltage-drop target

Estimate the copper conductor area needed to keep steady DC voltage drop below a chosen percentage.

Single-phase AC load current

Convert real input power, voltage and power factor into apparent power and approximate steady current.

Single-phase copper voltage-drop screen

Estimate the resistive part of voltage drop and cable heat for a two-conductor single-phase run.

Heating

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Heat-pump design-load coverage

Compare building heat loss with heat-pump and auxiliary capacity at the same outdoor design condition.

Heat-pump daily electricity

Convert useful heat from the heat pump and auxiliary heater into an ideal daily electricity estimate.

Cost per useful heat delivered

Compare input energy and cost for a useful heating demand and seasonal performance factor.

Hydronic heating flow rate

Convert a heating load and design supply-return temperature difference into a water-flow estimate.

Radiator output at lower water temperature

Estimate how a radiator’s published heat output changes at a different supply, return and room temperature.