The Pyramid to Smarter Building and Renovating

The Pyramid for Building & Renovating Smarter

Eco living is not a fad, in fact, it’s here to stay, and people are getting more serious about it. In fact, all house plans submitted to councils must now meet a minimum energy star rating. Builders, architects, and designers are becoming more conscious of the effects of eco-smart designs, and homeowners realise the benefits to their wallets and the environment. 

The 10 points in the house/pyramid highlight the foundation elements and cost/priority actions when building or renovating a home. These aspects ultimately make the home comfortable, less high maintenance, environmentally friendly, and energy efficient.

First of all, it’s important to understand, sustainability.  A wonderful foundation of information for this is Passive House.  It’s a very hard standard to satisfy, but if you get halfway there, you will be in the right place.

1. House plan

For a new house, sketch the house plan. Position living spaces, such as the kitchen, dining and lounge rooms on the north side, and utility areas and bedrooms in the south. By doing this, you ensure that living spaces benefit from the winter sun and the bedrooms stay cooler in summer. Remember that good design or bad design will cost the same amount of money!  In a retrofit, implement shading on north facing brick walls, extend eaves, put in place window shutters, to allow winter sun in, and disallow summer sun.  Install deciduous trees and creepers which may help you to protect thermal mass in summer and expose thermal mass in winter.

2. Summer and winter

Always consider the impact that the seasons have, particularly summer and winter, on the house. How will your design deal with the hot summer sun? And how will it handle cold winter winds?

Make sure you have external shading on the north side to protect interior living areas from the harsh summer sun. This approach will still allow the winter sun into your house when it starts to become a bit dark and dreary indoors as well as outside. This will also reduce the amount of artificial light needed indoors during winter.

3 & 4. Ventilation and Indoor Air Quality

Here we consider the importance of ventilation when building a well-sealed building envelope.  If you’re building an airtight home (especially below 0.5 ACH@5Pa), you must consider mechanical ventilation with energy recovery. These systems: provide 24/7 fresh air in living areas and bedrooms while exhausting stale air from the bathrooms, kitchen, and utility areas. They can recover up to 80% of the energy from the outgoing air. They are often ducted throughout the entire house. When combined with a high-performance building envelope, these systems maintain comfort and air quality with minimal loss.

5. Airtightness: Sealing Gaps and Cracks

The building envelope, your home’s external walls, ceiling, and floor, must be as airtight as possible. Before plastering, seal all gaps and cracks to minimise unwanted air infiltration and prevent energy loss from your home.

Every home, airtight or not, still needs controlled ventilation. Without it, you rely on uncontrolled air entering through cracks, which also lets your heating or cooling escape. The key is finding a balance: seal the building to prevent energy loss, then introduce the right amount of fresh air and exhaust the stale air, ideally via mechanical ventilation. Sealing the building envelope tight enough and at the same time providing the right amount of natural infiltration, requires implementing some smart strategies. The good news in all of this is that it can be done very cost effectively in both new construction and existing buildings. This ensures a healthy and energy-efficient home.

A blower door test measures air changes per hour (ACH) at various pressures. A good target for Australian homes is just above 0.5 ACH at ambient pressure. If you aim to go tighter, a mechanical ventilation system is essential.

6. Insulation consistency

There are several types of insulation available on the market

• Batts and blow-in insulation (trap air to resist heat flow)

• Reflective foils (reflect radiant heat in summer)

• Sheet insulation (for structural and high-performance needs)

Whatever insulation you choose, make sure it is installed correctly. Any gaps or holes in the insulation barrier could result in air leakage and energy loss. If you opt for downlights in the ceiling, remember that each creates a hole in your insulation, reducing its performance unless appropriately sealed and managed. This is a building regulation to prevent overheating of light fixtures.

7. Double glazing

Double-glazed windows are a good investment for energy efficiency as well as acoustic comfort. They reduce heat loss in winter and heat gain in summer, lower noise transmission, and can be enhanced with low-e coatings or films.

While more expensive upfront, they offer long-term savings and comfort. Do your homework to find the best solution for your climate and budget.

8,9 & 10. Heating, Cooling, Solar, Lighting, and Appliances

Having done everything to seal and insulate the building structure, it is time to decide how to heat or cool your house.

If you have followed the preceding steps in the upside down the pyramid to plan, then you will need very little heat in winter and almost no cooling in summer.

Perhaps a small, energy-efficient, split system heat pump in winter and a couple of ceiling fans in summer may be all you need.

And because the bedrooms are on the south side of the house, they’ll be cool in summer.

Then, with the money saved from heating and cooling, think of installing a heat pump hot water system.

If your budget allows for it, consider a mechanical ventilation system for the entire house. Especially in a well-sealed house, this system will provide fresh, filtered air all year round with minimal loss of energy.

It is also effective in reducing high levels of humidity, which in turn controls dust mites and mold growth.

Get these things right and then you can move onto the other things in the upside down pyramid, to help you cost effectively move to a more energy efficient home.

All these things are great and a complete no brainer when there are subsidies available, or if these things break and need replacing, Solar Panels and heat pump hot water systems, with subsidies can move further down the pyramid, from a cost perspective and they can also turn your home into a net contributor to the grid when you have your building envelope right.

Having done everything to seal and insulate the building envelope, you must now decide the systems to implement. If you have followed all previous steps your home should need minimal heating and cooling. You may only require: a small, efficient split system heat pump for winter and a few ceiling fans for summer. With bedrooms located on the cooler south side, and effective thermal design throughout, you can stay comfortable with less energy.

Additional considerations:

• Heat pump hot water systems are energy-efficient and eligible for rebates

• Mechanical ventilation systems maintain healthy air quality in airtight homes

• Solar panels, when paired with a well-designed envelope, can turn your home into a net energy contributor

With rebates available, some of these options move lower down the cost pyramid and become even more attractive.

By (Mr) Jan Brandjes