How We Build: Net-Zero Homes to the Highest Standard
When someone asks what a NeighbourWood home will be, the short answer is: a home that produces more energy than it consumes, protects its own systems, and costs less to live in than a standard new build. That’s what net-zero means in practice.
The longer answer involves the engineering decisions behind that outcome. Because net-zero isn’t a marketing term for us — it’s a measurable performance standard with a specific certification behind it.
BER A1: What It Actually Means
Every NeighbourWood home will target BER A1, the highest residential energy performance rating available in Ireland. To put that in context: current building regulations require approximately BER B2. Most new-build homes in Ireland achieve BER A2 or A3. BER A1 is a step beyond what anyone is required to build.
We will certify to the Passivhaus standard — the international gold standard for low-energy building, recognised in over 60 countries and independently verified by the Passivhaus Institut in Germany. It’s not a self-assessment. A third-party certifier tests your building and either it passes or it doesn’t.
Here’s what the specification requires:
Primary energy demand of no more than 15 kWh per square metre per year. A typical Irish home uses 150–250 kWh/m²/year. Our homes will use roughly one-tenth of that.
Air permeability of 0.6 air changes per hour at 50 Pascals pressure. In plain English: the building envelope will be so well-sealed that virtually no heat escapes through gaps, cracks, or poorly-fitted joints. This is tested with a blower door test on every single home.
Thermal performance that exceeds building regulations by a wide margin. Our specification targets wall U-values of 0.12 W/m²K, roofs at 0.10, floors at 0.10. Triple-glazed windows with U-values below 0.80. Every thermal bridge — every point where heat could escape through the structure — is designed out and independently certified.
The result: a home that stays warm in winter and cool in summer with almost no active heating or cooling required.
The Energy Systems
Passivhaus fabric gets you 90% of the way to net-zero. The integrated energy systems get you the rest — and then beyond.
Heat Pump
Your home will be heated by a heat pump — a system that extracts low-grade heat from the environment and amplifies it to heat your home and hot water.
For every 1 kWh of electricity the heat pump uses, it produces 3.5–4 kWh of heat. That’s a coefficient of performance (COP) of 3.5–4.0. Compare that to a gas boiler, which converts 1 kWh of gas into roughly 0.9 kWh of heat.
The practical difference: where a typical Irish home might spend €2,000–3,000 per year on heating oil or gas, a heat pump in a Passivhaus-standard home will cost approximately €200–400 per year to run. The building fabric does most of the work; the heat pump handles the rest with remarkable efficiency.
Solar PV
Each home will include a 6kWp rooftop solar array — enough to generate approximately 5,400 kWh per year in Irish conditions. That’s roughly equivalent to the total electricity consumption of an energy-efficient home.
In summer, you’ll generate more than you use. In winter, less. That’s where the battery comes in.
Battery Storage
A 10kWh home battery will store excess solar generation for use in the evenings and overnight. It shifts your consumption from peak rates to self-generated power and provides resilience during grid outages.
The battery also enables participation in grid services programmes. As Ireland’s electricity grid evolves, home batteries become increasingly valuable — both to the homeowner and to the national grid.
Mechanical Ventilation with Heat Recovery (MVHR)
In a home this airtight, you can’t rely on gaps in the structure for ventilation. Nor would you want to — uncontrolled air leakage is how homes lose heat, admit pollen and pollutants, and develop damp and mould problems.
Instead, each NWC home will use a Mechanical Ventilation with Heat Recovery (MVHR) system. It continuously extracts stale air from kitchens and bathrooms and supplies fresh, filtered air to bedrooms and living spaces. As the outgoing air passes the incoming air in the heat exchanger, it transfers over 75% of its heat — so you get fresh air without losing warmth.
The result: indoor air quality that’s consistently better than outdoor air, with no condensation, no mould risk, and no draughts.
Whole-House Water Treatment
Every NeighbourWood home will include an integrated water softening and treatment system. This isn’t a luxury add-on. It’s infrastructure protection.
Hard water is the silent killer of energy systems. Scale buildup in a heat pump reduces its efficiency by 10–25% within five years. That directly erodes the energy savings the system is designed to deliver. A water softener prevents this degradation entirely.
The installed cost is modest (approximately €1,450 per home), and the annual benefits are substantial: €620–1,110 per year in protected energy efficiency, extended appliance life, reduced cleaning products, and avoided repairs.
We include it as standard because it protects the infrastructure investment. A €275/year operating cost protects a €2,600–3,900/year energy saving.
How It’s Built
NeighbourWood homes will use precision-engineered modular timber frame construction. The panels are manufactured off-site in factory-controlled conditions, then transported and assembled on-site.
This method offers four advantages over traditional block-and-mortar construction.
Higher quality. Factory conditions mean consistent temperature, humidity, and quality control. No rain-soaked timbers. No rushing to close up before weather arrives. Every panel is built to specification in a controlled environment.
Faster build time. A modular timber frame home can be weathertight in days, not months. Site disruption is minimal. Foundations, services, and ground works are completed while the panels are being manufactured — parallel workflows that compress timelines significantly.
Less waste. Factory production generates roughly 60% less waste than on-site construction. Materials are cut precisely. Offcuts are recycled. There’s no skip full of broken blocks and leftover mortar.
Lower carbon footprint. Timber sequesters carbon rather than emitting it. A timber frame home locks away CO₂ for its entire lifespan. Concrete and steel — the dominant materials in traditional Irish construction — are among the most carbon-intensive materials on earth.
The Numbers
What does all this mean for your monthly costs?
A typical Irish home spends €2,600–3,900 per year on energy — electricity, gas or oil for heating, and associated standing charges. A NeighbourWood home’s energy costs will be effectively zero on a net annual basis. Solar generation, battery storage, and heat pump efficiency mean you’ll produce more energy than you consume.
Add the water treatment benefits — €620–1,110 per year in protected efficiency and avoided costs — and the total direct operational saving is €3,220–5,010 per year compared to a typical home.
Your annual fees will total €2,220 across three tiers: estate management (€850), woodland stewardship (€850), and energy infrastructure maintenance (€520). After fees, you’ll be €1,000–2,790 better off every year than a comparable homeowner.
That’s the conservative calculation using direct savings only. Add green mortgage rate discounts (BER A1 qualifies for the best rates — saving approximately €2,460/year on a €450k mortgage) and avoided future retrofit costs (typical Irish homes face €50,000–100,000 in energy upgrades by 2035 under tightening regulations), and the full annual benefit rises to €6,760–11,850.
Why We Will Build This Way
We will build to the highest standard not because we have to, but because the 10:1 Model requires it.
The Woodland Bank generates carbon and biodiversity value that grows over decades. The homes need to match that permanence. A poorly-insulated house with a gas boiler would undermine the entire proposition — you can’t claim to solve the climate crisis while building homes that contribute to it.
And the economics have to work for homeowners. If our fees aren’t offset by genuine savings, the model fails. So we’ve designed the specification to deliver measurable financial benefit from day one, not just environmental credentials.
Every decision in the specification serves the same purpose: a home that costs less to run, lasts longer, performs better, and leaves the world measurably better than it found it.
That’s not aspiration. That’s engineering.
This is the third in a series explaining how the NeighbourWood model works. Read about the 10:1 Model and the Woodland Bank. To follow our progress, register your interest.