Heating & Cooling
6 questions, answered from real HiPer Haus projects across South Australia.
Sizing, system types and why airtight, well-insulated homes need a different approach to heating and cooling than a standard build.
From the field
“One thing we've learnt working across airtight, well-insulated builds is that the heating and cooling system almost always gets specified before the envelope's performance is properly understood — meaning it's sized for a home that, once finished, doesn't actually exist.”
— Jonathen Hindry, HiPer Haus
Mistakes we see in sizing and system selection
- Systems sized by floor area alone, ignoring insulation, glazing and airtightness — usually resulting in an oversized, short-cycling unit.
- Evaporative cooling specified in an airtight home, undermining the whole ventilation strategy.
- Zoning added after the fact rather than designed in from the start, leading to uneven comfort room to room.
What size air conditioner do I need?
Sizing depends on your home's heating and cooling load — driven by floor area, insulation, glazing, orientation and airtightness — not floor area alone. A leaky, poorly insulated home and an airtight high-performance home of the same size can have very different load calculations and need very differently sized systems.
Related calculator → Air Conditioner Size Calculator
Read the full guide → Heating & Cooling for Passive Houses
People also ask: How do I calculate my home's heating and cooling load?
Should I use ducted, split system, or hydronic heating?
Each has trade-offs in cost, zoning flexibility and comfort, and the right choice depends on the home's layout, airtightness level and budget rather than a single “best” answer. On our recent Passivhaus projects, smaller and simpler systems have performed surprisingly well because the load they need to meet is so much lower.
Read the full guide → Heating & Cooling for Passive Houses and High-Performance Homes
People also ask: What is a bulkhead system and is it worth it?; What size air conditioner do I need?
Why doesn't evaporative cooling suit an airtight home?
Evaporative cooling relies on a constant supply of outdoor air moving through the house and out again — the opposite of how an airtight, MVHR-ventilated home is designed to operate. It also adds significant humidity, which is exactly what airtight construction is trying to manage. Reverse-cycle systems are a better fit for high-performance homes.
Read the full guide → Heating & Cooling for Passive Houses
People also ask: Does a high-performance home need less heating and cooling capacity?
Does a high-performance home need less heating and cooling capacity?
Yes, often substantially less. Airtightness and insulation reduce uncontrolled heat loss and gain, so the heating and cooling load calculation for a high-performance home is typically much lower than for an equivalent standard build — meaning smaller, cheaper systems can maintain the same or better comfort.
Read the full guide → Heating & Cooling for Passive Houses
People also ask: Does airtightness reduce heating and cooling costs?; What size air conditioner do I need?
What is a bulkhead system and is it worth it?
A bulkhead (or cassette) system conceals ducted air conditioning within a section of ceiling rather than requiring a full ceiling void, offering some of ducted's zoning and aesthetic benefits with less structural impact. Whether it's worth it depends on your home's layout and design — it's one of several options worth weighing against split systems, full ducted and hydronic.
Read the full guide → Heating & Cooling for Passive Houses
People also ask: Should I use ducted, split system, or hydronic heating?
How do I calculate my home's heating and cooling load?
Load depends on floor area, insulation levels, glazing performance, orientation, shading and airtightness — our calculator gives a practical estimate you can use before speaking with an installer, based on inputs specific to your home rather than generic rules of thumb.
Related calculator → Air Conditioner Size Calculator
Read the full guide → Heating & Cooling for Passive Houses
People also ask: What size air conditioner do I need?
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Written by
Jonathen HindryFounder of HiPer Haus. ATTMA Level 1 Airtightness Tester, Certified Passive House Tradesperson and 25+ year plumber — blower door testing, MVHR design and heat pump hot water across Adelaide and South Australia.
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