March 6, 2019 0


We were exhibiting at the Henley House and Garden Show last weekend, promoting sustainable architecture to visitors and other exhibitors alike. We had lots of interesting conversations, so I thought I’d write about one of the main themes when discussing sustainability (something which is one of my growing pet hates…).

There is a very common misconception that the way to make your home more sustainable is to put solar panels on the roof. I had a lot of discussions about this over the weekend, and I find it surprising that most people don’t see anything beyond this, unless they’ve really started to look into how buildings perform.

My personal view is that solar panels fall into the ‘eco bling’ bracket, and are really the last step on the road to reducing your home’s impact, after you’ve improved its performance to reduce heating and other energy demand, installed efficient systems, reduced the impact of materials, improved occupant comfort and health, and then (only then), might it be a good idea to offset (some of) the remaining electricity demand with solar panels!

I’m all for renewable energy sources, but there are some significant issues with solar panels that make them unattractive, namely:

  • The cost vs. payback argument is worse now than in the past due to reduction of government incentives
  • They are a relatively inefficient source of electricity, and if you’re using them for heating (via a heat pump), there is less sunshine in the winter when you need that power. Battery storage might be an answer to day / night availability (say for car charging), but that’s more cost, and doesn’t help with inter-seasonal storage (i.e. you can’t store electricity from sunshine in summer and use it in winter)
  • They have a relatively short lifespan. Efficiency of solar panels is shown to reduce gradually over time, and after 20-25 years they are likely to need replacing. If your payback period (the investment compared to the annual saving of not buying electricity from the grid, plus any incentives you receive), is close to that period of time, it makes the economic argument quite poor
  • They are not recyclable. Although manufacturers will tell you solar panels are made of valuable materials that can be recycled at end-of-life, there just aren’t systems in place globally to process solar panels when they’re removed from buildings. This means very valuable resources are being simply put into landfill, radically increasing their whole life environmental impact (due to the materials and processes which go into making them in the first place)
  • They’re not very pretty (I threw that last one in as personal opinion, but they can spoil your great design aesthetic!)

So what’s the solution?

Make your home into a high-performing machine:

  • Reduce demand first – make your home super-efficient by insulating it and reducing air leakage
  • Install high quality windows and doors with low u-values
  • Use low-energy fixtures and fittings
  • Apply passive design principles (if you’re doing building work) to take advantage of solar gain for heating in winter and use shading devices to reduce overheating risk in summer
  • Ensure good ventilation pathways to improve indoor air quality and help reduce summer-time overheating risk

All these things reduce heating and other energy demands.

Now install high-quality, efficient services, ideally using electric systems for heating (both space heating and hot water), and if you’ve gone to a really low-energy standard like Passivhaus, you’ll need a mechanical ventilation and heat recovery unit (MVHR) too. Now you have a low energy (and therefore low emissions) home!

Remaining electricity demand (for a heat pump, appliances, lighting, car-charging etc.) can then be generated on-site by a renewable energy source (let’s say solar panels) if that’s what you really want to do, but instead you could get a 100% renewable energy tariff, and save yourself the cost!

You won’t have the eco-bling solar panels unfortunately, but you will still have a home that’s cheaper to run, has vastly lower environmental impact, is more comfortable to live in (draught-free and cosy in winter and cooler in summer), and when designed properly will be more resilient to climate change.

Get in touch with us if that’s the type of house you want to live in! We design-in sustainability, so you’re not paying extra to add it on later.