Going for an upgrade

This Issue This is a part of the Existing houses feature

By - , Build 147

Older houses often don’t perform as well as new ones. Fortunately, there are plenty of ways to upgrade performance as well as modernise for form and function.

BUILDING UPGRADES can be either related to performance or to appearance and features. Meeting the requirements of the Building Code is the minimum for performance upgrades, but you can aim higher.

Bar continually rising

Building codes and standards are regularly reviewed and updated, and as a result, the performance level required of our domestic buildings increases over time. This means existing buildings are falling further behind in areas such as energy efficiency.

How far behind depends on the age of the house. Around 70% of our current housing stock was built before the first energy efficiency regulations came into force.

In 2010, the BRANZ House Condition Survey estimated that 70% of New Zealand houses had full ceiling insulation, although some of it was insubstantial. Thirty percent of houses have less than 50 mm of insulation.

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12 performance upgrades

There are plenty of easily achievable ways to upgrade existing houses to perform better. Here are some things to consider.

Increase insulation

For existing houses with accessible roof spaces, adding additional or installing new higher-performance insulation is typically a relatively simple and cost-effective upgrade option.

Upgrading insulation for skillion roofs is more difficult but is possible (see options in Build 146, page 36).

Adding subfloor insulation is relatively easy if the house has a suspended floor. Existing foil insulation is likely to be dirty and tarnished, and replacing it with a bulk insulation will add a significant benefit.

Replace electric heaters with a heat pump

After upgrading the insulation, changing to a more energy-efficient space heating system reduces energy costs. For comparative space heating running costs, see www.energywise.govt.nz and search ‘efficient heating’.

Also consider incorporating thermal mass as part of any renovation or addition to absorb then release free heat from the sun.

Go for double or secondary glazing

In even the warmest climates, windows become the largest area of heat loss once walls are insulated to higher levels. Replace single glazing with double glazing or secondary glazing.

Replacing existing single glazing can be relatively simple if aluminium frames can accommodate the thicker insulated glazing units. Improving performance is harder, and correspondingly more expensive, for old aluminium and timber frames, as the insulated glazing units are not so easily fitted.

Get the flue

In most modern houses, there is insufficient ventilation to remove the considerable amounts of moisture generated by unflued fixed and portable gas heaters.

Where gas is retained as an energy source, the unit should be flued to the outside air to effectively remove the combustion gases and the water.

Vent extractors outside

Internal moisture is a significant problem in New Zealand dwellings and is generally due to a lack of ventilation.

Install or upgrade extract systems in bathrooms and kitchens that vent to the outside so the moisture-laden air is removed as quickly as possible. Replace old kitchen rangehoods that simply circulate air within a space.

Harvest rainwater

The recent summer highlighted that in many parts of New Zealand, water can be a scarce commodity. Capturing rainfall is an easy option for most dwellings and reduces demand on community water supplies.

Installing a tank adjacent to a downpipe and some slight inexpensive modifications to that downpipe allows water to be collected for gardens and car washing.

Put in retractable sunshades

Summer overheating is a problem in New Zealand houses when there is no control over how much sun gets into the house on hot days. Adding retractable awnings gives the opportunity to limit the summer overheating while allowing (when retracted) the desirable winter sun into the building.

Add passive ventilators to windows

Houses are becoming more airtight, and increasingly people don’t open windows because of security and other concerns.

Incorporating passive ventilators into existing windows can provide some secure ventilation when the ventilators are left open.

Make lighting more efficient

The simple task of changing lights to a more efficient source of illumination, such as LEDs, will help reduce energy consumption.

Installing a reflective tube with an internal mirror finish that runs from outside to inside will also intensify and reflect natural daylight.

Attend to under the floor

Bracing subfloors provides lateral stability to adequately resist loads from earthquakes. This can be done by adding subfloor braces or fixing sheet material such as plywood or fibre-cement to the jack framing between the floor structure and the ground.

Damp subfloors can be dealt with by ensuring existing ventilation is open and adding new ventilation openings or covering the ground with polythene to stop the moisture evaporating. Also check there are no leaking pipes depositing water under the floor and no groundwater flowing under the building.

Stop the breeze

Draughtproofing old timber doors and windows is the most cost-effective way of saving energy.

As little as $10 worth of self-adhesive rubber draught stripping can reduce draughts and therefore heat loss around opening timber sashes and external timber doors and pay quickly for itself.

Remove unused chimneys

Old, unused open-fire chimneys are a significant source of heat loss and should be removed or at least sealed off to help retain heat.

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Five non-performance upgrades

These upgrade options are more about amenity or appearance rather than performance:

Retrofit the kitchen

Kitchens are the heart of the modern home, but they date quickly. Worktops are the most effective improvement. Revamping tired cupboard doors completely changes the feel of kitchens, bathrooms and bedrooms.

Extra rooms

If the size of the section allows it, additional spaces for living and sleeping can be gained by extending out or up.

Enhance indoor/outdoor flow

Installing new doors can enhance indoor/outdoor flow – often in conjunction with a new deck. Where the external weatherskin and structure of the building is modified, a building consent will likely be required.

Get a deck

The level of amenity provided by a timber-slat deck adjacent to the building depends on the situation. On sloping sites, they effectively create an accessible, flat usable area without extensive earthworks.

Open up small internal spaces

A builder, professional structural engineer or architect will be needed to determine if a wall is loadbearing. Drawings and a building consent will be required before any wall is removed. Potential complications include the existing plumbing and wiring.

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