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Eco-upgrade to a Christchurch home

The purpose of this project was to remodel and upgrade some parts of the house while at the same time improving its overall sustainability, as measured under the Green Homes Scheme, to achieve as high a Star Rating as practical.

The project was completed by David Bryce from Eco Solutions in Christchurch.

Living room North West corner and low windows to catch warm air from rock walls

Rather than a rebuild, alterations were decided on as the most sustainable option.
These include:

  • Increasing insulation in the ceilings and walls and installing under floor insulation and double glazing
  • Adding a thermal mass section of floor, internal rock wall and thicker gib lining to increase passive heating
  • Converting a room to a solarium for food production and a source of passive solar hot air
  • Relocating and upgrading the kitchen to be more functional and energy efficient
  • Upgrading the wood burner and hot-water cylinder, adding a wetback heater and refining the existing solar water heater.
  • Refining cross-flow and passive stack ventilation and increasing natural lighting
  • Upgrading plumbing to utilise roof-water for non-potable purposes and to recycle grey water.

The alterations are designed to:

  • Reduce: condensation; electric power consumption and reliance; water consumption; smoke emissions; maintenance costs; internal toxins and waste.
  • Increase: food production; ventilation; comfort levels; natural lighting; safety and resistance to natural disasters; and use of sustainable products and materials.

All designers, contractors, manufacturers and suppliers were required to be conversant with sustainability principles, use appropriate techniques and processes and comply with an approved Environmental Management Plan. All products and materials were chosen as the most sustainable in the circumstances.

Emphasis was placed on proving a need for any work, minimisation of waste and re-use of any significant materials and features.

Recycled timber joinery in kitchen

Documents & design

Target: ensure all contractors apply sustainable practices, all design emphasis on sustainability and enhancing house character, guideline pay-back period 20 years for new measures.

Measures: Assessed existing building character and what parts of building could be retained and what needed to be upgraded. Specifications included sustainability measures and Environmental Code + requirement for waste management plans for all contractors. Carried out energy audit to identify heat losses and upgrading required. Carried out ALF energy analysis on final design. Carried out in-house Green Home Scheme analysis on final design. Ensured alternative/ backup systems would be available for all essential services.

Internal thermal mass site rock wall and wood burner


Target: minimise dismantling(avoid any demolition) and maximize reuse of materials and recycling.

Measures: reused or recycled all salvageable materials including timber, fittings, bricks, iron, doors and windows, kitchen joinery, timber flooring and walling, skirting, architraves and bench tops.

Reuse of doors, windows and new untreated timber (New Zealand Fir)


Target: minimise damage to garden and re-level lawn.

Measures: relocated plants likely to be affected, avoided soil compaction by using walking planks, separate stockpiles for surplus concrete, rock, clay and soil. Layered and leveled stockpiles for native grass lawn.


Existing: 1920’s rimu timber bungalow with iron roof, lounge added 1981 in treated pine timber + concrete floor, washhouse + toilet + spa + study added in 1984 in treated pine timber + concrete floor, upstairs 3 bedrooms + bathroom/toilet added 1990 in treated pine.

Target: Ensure need, durability, versatility, non-toxicity, low embodied energy, recyclable, locally sourced, minimal environmental impact, low and efficient resource use.

Measures: removed toxic materials, replaced with eco materials, used low VOC paints, solid natural or recycled sustainably sourced timbers, wool insulation, marmoleum flooring in kitchen, part gib walls and ceilings, flax wallpaper, part wool carpet, part tiling and part varnished rimu flooring, concrete with 30% of cement substituted with flyash. Treated timber used only where required, otherwise fir, oregon or rimu.


Existing: Some fiberglass batts in ceiling and most walls, no under floor, thermal drapes.

Target: Ceiling R5, walls R3.6, floors R2.4, sustainable materials.

Measures: eliminated draughts, extra wool batts throughout, +plywood under floor and extra wall bracing, double glazing in timber frames, + low e on solarium roof with aluminium frames. Achieved Ceiling R4.4+ply+match lining, walls R2.2+ply+13mm gib, floor R3.2+ply.

Wool blankets and ply under floor


Existing: Roof collection for garden, ceiling header tank, garden swales, low use.

Target: Collect and reuse all site water. Minimise use and leakages.

Measures: Ensured no water entering ground under house, repaired spouting and discharges, collecting south facing roof water in storage tank and supplying dual flush toilet cisterns and solarium water, upgraded ceiling tank to retain low pressure hot water, kitchen filter for drinking water, collecting grey water from bathrooms (and wash-house proposed) for garden irrigation(water lillee system), (propose north facing roof water for aquaculture system), (propose solar pump up to new storage tank near road), discharge storm water from hard ground surfaces to swales, low/medium flow shower and taps, hot water efficient delivery with manifold system and well insulated.

1. Polythene on ground under floor 2. Water Lillee system 3. Roof water re-use

Existing: 18 year old solar panels, short draw-off lines, h/w cylinder 27years old-no wrap.

Target: Fully renewably powered + electric backup, reduce water heat losses.

Measures: Checked and upgraded solar panel operation, installed new A grade insulated hot water cylinder, added wetback to replaced wood burner.

Water heating

Existing: 18 year old solar panels, short draw-off lines, h/w cylinder 27years old-no wrap.

Target: Fully renewably powered + electric backup, reduce water heat losses.

Measures: Checked and upgraded solar panel operation, installed new A grade insulated hot water cylinder, added wetback to replaced wood burner.

Space heating and cooling

Existing: Solar gain + old wood burner, poor heat distribution.

Target: Fully renewable heat in all main rooms.

Measures: Removed/pruned evergreen trees shading house north wall, retain deciduous vines, replaced wood burner with more efficient model (pyroclassic IV), increased glass to appropriate surface area, installed double glazing, checked eave widths, increased internal thermal mass with new concrete floor slab and tiles and thicker gib board, replaced lounge carpet with tiles on sun strike strip, added feature rock wall fireplace for extra thermal mass in living room, converted old study to solarium vented to house, installed vents above doors for better air circulation. Warm air circulates throughout house by natural convection (passive stack ventilation). Warm air from outside rock wall vented inside through low windows. Minimal windows on south wall to introduce cool air on hot summer days.

1. Thermal mass suspended concrete floor with tiles for solar heat storage 2. High level windows for passive heat circulation 3. Solarium at North East corner

Ventilation and air quality

Existing: Natural, passive.

Target: Adequate air exchange and dehumidifying.

Measures: Extractor fans installed for kitchen and bathroom, cross- flow opening windows, reduced carpet areas, minimise synthetic materials.

Cross-flow ventilation


Existing: Sewer discharge, outdoor clothes line, internal fireside airing and electric dryer.

Target: Water reuse and natural drying.

Measures: Washing with ecoballs and discharge to garden, outdoor clothes line and internal fireside airer.


Existing: Compact fluorescent, some during daytime.

Target: Natural daytime light, necessary night-time energy efficient lights.

Measures: Extra windows, solar tubes in toilet & bathroom, LED efficient lighting.

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More Photographs

Water Lillee system

Thermal mass suspended concrete floor with tiles for solar heat storage

High level windows for passive heat circulation

Solar water heating panels and low-emission wood burner flue

Solarium at North East corner

The project was completed by David Bryce from Eco Solutions in Christchurch.


Existing: Historical use about 25kwh/day.

Target: 5kwH/day, minimise internal electromagnetic radiation.

Measures: Upgrade solar water heating system and install wetback, reduce hot water heat losses, increase insulation throughout, increase internal thermal mass and passive solar warming, increase natural lighting, install energy efficient appliances, create passive stack ventilation, install PV panel for outdoor lighting, confined wiring and avoided wiring near bed-heads. Electricity use now averaging 8kwh/day.

Solar water heating panels and low-emission wood burner flue


Existing: Old electric oven and cooktop, wood burner cooktop, gas bbq.

Target: Maintain alternatives, reduce electricity.

Measures: New gas cooktop with electric oven, new wood burner with cooktop and simple oven, new outdoor wood oven.

Hot water cylinder, wetback pipes, solar pipes and control panel

Safety and security

Existing: Some signs of building settlement/movement and significant wall and concrete cracking from earthquakes, security bolts and some window security latches, some safety handrails.

Target: Building able to withstand moderate earthquakes and climate change events, including loss of electricity and water supply, suitable for disabled and secure.

Measures: Structural engineering assessment and design of alterations, extra timber bracing and steel beams and ply walling where desirable, emergency preparedness kit, ramp to front door(proposed), extra handrails, extra window security latches and water storage for on-site fire protection.


Existing: Poor reception on portable phones, exposed wiring.

Target: Improve efficiency, reduce radiation.

Measures: Replace CRT with LCD TV, replace computer screens with LCD, consolidate telephone outlets and wiring, reduce wireless devices.

Solarium at North East corner

Waste management

Existing: Mini containers for kitchen, tidy bin system outside, garden compost.


Existing: Old fridges, freezers, stove and dishwasher.

Target: Maximise energy and water efficiency.

Measures: Reduce to one efficient fridge and freezer. Upgrade to energy/water efficient stove and dishwasher.


Target: More sustainable outdoor facilities, improved indoor/outdoor connections and re-use surface water.

Measures: Plantation grown, on-site milled macrocarpa or recycled timber decking and furniture, permeable paving or surface water directed to garden swales, site-rock retaining walls. Solar powered security and path lighting.

1. Site-rock retaining walls 2. Solar powered security and path lighting

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Posted by on 03/11/2015 03:02 PM

Eco upgrade to a Christchurch home
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