RefurbN16

Tag: Controls

  • Sustainable Refurbishment – Towards an 80% Reduction in CO2 Emissions

    The UK’s building regulations didn’t start to consider energy consumption until the 1960s, when very basic requirements to conserve energy were placed on house builders. These requirements have slowly been tightened over the decades and the introduction of the Code for Sustainable Homes has accelerated this in recent years.

    The intention is that new build homes built from 2016 will be zero carbon (although the exact definition of ‘zero carbon’ in this case is still up for grabs). The problem is that the UK’s housing stock is the oldest in the developed world, with 8.5 million properties over 60 years old and an estimated 24 million homes built up to 2016 expected to still exist in 2050.

    Zero carbon new build homes are definitely needed so that new homes don’t add to emissions, but all of the carbon reductions will have to happen in homes that have already been built.

    In the previous post we looked generally at a whole house approach to sustainable refurbishment. The Energy Saving Trust has recently published an interesting new publication which looks at this in more detail and points the way towards an 80% reduction in CO2 emissions in existing homes. This guide is aimed at homeowners as well as housing developers and builders and is clearly written and nicely presented.

    It gives an excellent overview of the energy efficiency measures that can be implemented in the UK’s homes including the different types of wall, roof and floor insulation, improving windows and doors, increasing air tightness as well as efficient heating and hot water systems and lighting and appliances. Also covered are microgeneration, water efficiency, waste and recycling and even climate change adaptation.

    If you want to get a good picture of what needs to be done to our homes, then this is a good starting point. Hopefully it will stimulate you to consider which of these measures can be applied in your home.

    The Energy Saving Trust has lots of interesting technical guidance. More information can be found here.

  • Heating Controls Pt 2 – Programmer and Room Thermostat

    This one often causes vigorous disagreements, but I’m going to stick my oar in and describe how I think the programmer and room thermostat (see Pt 1 for a description of these controls) should be set in a home.

    The very quick version is:

    1) Work out what the minimum comfortable room thermostat setting for your home is and then

    2) Set the heating to come on for as little time as possible

    It sounds simple but there are some subtleties to it that I’ll discuss now. Unfortunately there isn’t a great deal of hard research to go on. This is my best guess and I’m happy to hear contrary views. If anyone can dig up proper research, I’d appreciate it.

    Now first up, there is some evidence to suggest that if the fabric of the house is cold then you need to heat the air to a higher temperature in order to feel warm. The thinking goes that the additional radiated heat from the walls makes a difference to comfort and as a result, if you let the walls warm up you can get away with a lower air temperature.

    This is borne out by plenty of anecdotal tales of people changing from bimodal heating (having it on twice a day) to continuous heating but setting the room thermostat to a lower temperature and reporting energy savings while still being comfortable.

    Unfortunately it’s very difficult to compare two different heating patterns because your home’s energy consumption is so dependent on the outside air temperature (it is possible though by taking regular meter readings and doing a degree day analysis, but that’s for another time).

    Turning your thermostat down does lead to substantial savings. Everything else being equal, heating consumption is cut by about 10% per degree you turn it down. But having your heating on all the time? I’m certain that’s not efficient because you’re heating the home when you’re fast asleep or out of the house and I’m sure you could at least shut it down for a few hours in the middle of the day or night.

    If your home is not very responsive (i.e. it takes a long time to heat up), which many solid wall homes are, it might take a long time to heat up the walls and so it might seem like you’re ignoring the second part of the above advice.  might mean that you need to have the heating on for quite a while in order to get the fabric of your home up to temperature.

    So here is my patent pending method for setting your heating programmer and room thermostat:

    A bit of experimentation is called for…

    Stick your heating on for a good length of time on a reasonably chilly day and let the fabric of your house completely warm up and stabilise at a higher than usual temperature. Then start lowering the room thermostat until you get to the lowest temperature at which you are still comfortable. Depending on your home it may take a little while to let the temperature adjust.

    Next turn your heating system off and note how long it takes to cool down enough so that you’re starting to feel a wee bit nippy. This is your home’s cooling down time, we’ll call it C. When your home’s cooled down completely, turn it back on and work out how long it takes to get back up to the comfortable temperature. This is the warming up time, W.

    You then want to set your heating so that it comes on W minutes before you wake up in the morning and switches off C minutes before you leave the house. Set it to do the same before you get home in the evening / go to bed.

    If you have it on any longer than this, you’re heating your home unnecessarily, but do bear in mind that it might take a while to get the fabric of the house up to the right temperature.

    Does that make sense? It’s not an exact science but this is the best I’ve been able to come up with. As I said, comments gratefully received!

  • Heating Controls Pt 1 – Introduction

    Given that it’s bloomin’ freezing outside, I thought I’d write the first post on setting your heating controls.  This post will be an overview to the whole set of controls and it’ll take a few more posts to cover the whole lot.  For many this is a confusing subject so hopefully this post will help shed some light on a difficult area.

    Ideally your heating system should have at least 3 basic controls: a boiler thermostat, a room thermostat and a programmer. We’ll deal with them in reverse order.

    The programmer has overall control over when the boiler is switched on and off. It doesn’t have any temperature setting, just time settings. They come in varying degrees of sophistication from the most basic (which I unfortunately have) which can’t control the hot water and heating independently, to all singing and dancing, fully programmable digital devices. If the programmer is set to on, it doesn’t mean the boiler will be chugging away all of the time – the boiler should kick in and out in order to maintain a comfortable room temperature.

    This overall house temperature is set by the room thermostat, which is usually found in the hallway or living room of a home. It senses the temperature of the room and tells the boiler to switch on if it is below the set temperature and switch off if it rises above it. As a result your room temperature will bobble up and down slightly above and below the set temperature. The room thermostat can’t override the programmer so it will only have an effect if the programmer is in its on phase.

    The boiler thermostat is mounted on the boiler and controls the temperature of the water flowing out of the boiler and into the pipework and radiators. It tells the boiler how long to burn for in order to raise the water to the set temperature.This control is frequently overlooked and is usually the least well understood thanks to generally poor design.

    In an ideal world, all of these three controls will work together in perfect harmony to maintain the temperature of your home. By setting them correctly you can achieve this with minimum energy consumption.

    Clear? As mud? Post a comment below if you want me to clarify anything. I’ll be going into more detail on this very soon.