Should I replace my boiler with a heat pump before upgrading insulation?
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No. Upgrading the building envelope must come first. An uninsulated, leaky structure requires a massive heat pump running at high flow temperatures (60°C+), which slashes its efficiency and leads to huge power bills. Insulating first allows you to choose a much smaller, cost-effective heat pump running at an efficient 35°C flow rate.
Does sealing my home cause indoor mold and trapped humidity?
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Only if you seal the house without installing continuous mechanical ventilation. The core principle of building science is build tight, ventilate right. When airtight membranes are paired with an MVHR system, stale moist air is continuously removed while transferring over 90% of its thermal heat to incoming fresh, filtered air.
What is the difference between U-value and airtightness (ACH)?
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A U-value measures conductive heat transfer through solid materials (walls, roofs, glass) in W/m²K. Air Changes per Hour (ACH) measures convective thermal loss from air physically leaking through gaps and seams under pressure. A home needs both low U-values and a low ACH (ideally below 1.0 ACH @ 50Pa) to operate efficiently.
Can I use greywater directly in my garden without treatment?
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Untreated greywater contains organic oils, skin cells, and soap surfactants that turn foul within 24 hours if stored in tanks. It can only be distributed safely when applied immediately via sub-surface drip irrigation beneath mulch, or after running through a bio-sand reed filter bed.
Why are lime-based mortars preferred over Portland cement on older homes?
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Standard Portland cement is dense and vapor-impermeable. When moisture enters an older solid brick wall, hard cement traps the water inside the softer brick, leading to frost spalling and internal dampness. Lime mortar is flexible and vapor-open, allowing moisture to evaporate freely.
How much roof area is required for meaningful rainwater harvesting?
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Every square meter of roof catchment yields approximately 0.8 liters of filtered water per millimeter of rainfall (accounting for gutter splash and pre-filtration loss). A 100m² roof in an area with 800mm annual rainfall can collect roughly 64,000 liters of soft water each year.
Is triple glazing truly necessary in temperate climates?
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Yes, but not just for energy savings. The interior glass temperature of standard double glazing drops to around 14°C on freezing nights, creating uncomfortable convective drafts and downdrafts. Triple glazing maintains an interior surface temperature above 18°C, preventing condensation and preserving comfort right beside window openings.