How can i make my home greener?

Energy ef­fe­ciency ex­pert Nigel Humphrey on keep­ing your home com­fort­able while also cut­ting bills

Real Homes - - Contents - Nigel Humphrey is an ar­chi­tect and the prin­ci­pal at MAS Ar­chi­tec­tural and En­vi­ron­men­tal De­sign.

It seems sim­ple, doesn’t it? Use less energy, pro­duce less CO2, and wear thicker sweaters. But be­ing cold isn’t much fun and, af­ter the win­ter we’ve just ex­pe­ri­enced, nei­ther is see­ing our energy bills mount up. So what can you do to make your house cheaper to run, more com­fort­able and eco friendly, and how much will it cost?

Whether your house is new or old, the rules are the same:

Keep the heat in and the cold out. The best energy is free and zero CO2.. Use as lit­tle im­ported energy as pos­si­ble, and don’t waste it.

The trick is work­ing out ex­actly how to do all of that. There’s so many de­ci­sions to make; which in­su­la­tion and how much? What sort of boiler? Ra­di­a­tors or un­der­floor heat­ing, and what con­trols? What do you do first, and what will be most cost ef­fec­tive?

Use­ful to know

First, ac­cord­ing to Gov­ern­ment sta­tis­tics on energy us­age in the UK, on av­er­age about 63 per cent of your bills go to space heat­ing, 11 per cent to wa­ter heat­ing, 24 per cent to light­ing and ap­pli­ances, and three per cent to cooking. The av­er­age UK house­hold is about 85m2 and spends about £600 on gas, (mostly space and

wa­ter heat­ing) and £400 on elec­tric­ity, (lights and ap­pli­ances), which equates to about 268Kwh/m2/year. Gen­er­ally speak­ing, the elec­tric­ity de­liv­ered to your home pro­duces a lot more CO2 than the gas does.

Sec­ond, our per­cep­tion of com­fort is af­fected by the rate at which the air tem­per­a­ture around us changes. If there’s a cold draught, the tem­per­a­ture change will be rapid and you will feel chilly. A room at 21°C with cold draughts will feel colder and less com­fort­able than a room at 19°C with no draughts.

Third, the av­er­age UK dwelling has be­tween five to 10 air changes per hour, mean­ing that the air in your house has to be heated to a com­fort­able tem­per­a­ture five to 10 times an hour. A very energy-ef­fi­cient house might have less than two air changes per hour.

easy wins

You can save about £30 a year just by turn­ing ap­pli­ances off standby. Re­duce hot wa­ter us­age by tak­ing a shower in­stead of a bath and by fit­ting a wa­ter­ef­fi­cient show­er­head – sav­ing up to £75 a year for a fam­ily of four, as well as £120 if your wa­ter us­age is me­tered. Switch­ing to LEDS might cost £100 in the av­er­age home but will save £35 a year. Turn­ing off the lights when they’re not be­ing used saves £14 a year. And when your fridge, freezer or wash­ing ma­chine stop work­ing, re­plac­ing them with energy-ef­fi­cient A++ rated ap­pli­ances will give more sav­ings.

Home im­prove­ments

Heat­ing spa­ces ac­counts for more than half the av­er­age energy con­sump­tion, but it can be sig­nif­i­cantly re­duced by in­su­lat­ing the build­ing fab­ric (floors, walls, ceil­ings, roof spa­ces). Is­sues to con­sider are, where to in­su­late, (in­ter­nally, cav­ity, or ex­ter­nally on walls), what in­su­la­tion to use and how much, and to be aware of cre­at­ing a po­ten­tial for con­den­sa­tion and damp. To avoid this, wipe away con­den­sa­tion when you see it, make sure rooms are prop­erly ven­ti­lated, use a de­hu­mid­i­fier, or fans in the kitchen and bath­room, and en­sure there are no ar­eas where damp can pen­e­trate, ei­ther through struc­tural de­fects, leaky pipes or lack of a work­ing damp-proof course.


There are many dif­fer­ent types of in­su­la­tion, they vary a lot in cost and in their own en­vi­ron­men­tal im­pact. As with many ma­te­ri­als, the less pro­cessed

‘Our per­cep­tion of com­fort is af­fected by the rate at which air tem­per­a­ture changes. A room at 21˚C with draughts will feel colder than one at 19˚C with no draughts’

it is and the nearer to its nat­u­ral state, the less the amount of energy that’s used to pro­duce it (em­bod­ied energy) and the less pol­lut­ing it’s likely to be.

The loft is prob­a­bly the eas­i­est in­su­la­tion job and is one that you can do your­self. It could save as much as £225 a year. Floor in­su­la­tion could save £75 a year, cav­ity and solid wall in­su­la­tion be­tween £75 to £250 a year. This is work best done by pro­fes­sion­als, so they’ll cost more, but there may be grants avail­able. Good places to check whether there are any are, Nest­ if you live in Wales, and the Energy Grants Cal­cu­la­tor at­cu­la­tor

Draught re­duc­tion

Cut­ting down the draughts, and the num­ber of air changes per hour (in­fil­tra­tion), can also greatly re­duce the heat­ing load. How much is saved will de­pend on how ef­fec­tively this is done, but halv­ing the in­fil­tra­tion rate can halve the energy load. If there are fewer draughts it also be­comes pos­si­ble to re­duce the set tem­per­a­tures, and ev­ery de­gree of re­duc­tion will save about £30 a year.

In older build­ings draughts are ev­ery­where – round the win­dows ➤

‘Re­new­able heat sys­tems are de­sir­able if you want to be green, but only re­ally be­come cost-ef­fec­tive once you’ve got the build­ing work­ing ef­fi­ciently’

and doors, through the cav­ity walls, through air bricks, around sock­ets and light switches, through beam ends, down the chim­ney and be­tween floor­boards. This is partly be­cause tra­di­tional UK build­ing prac­tice re­lied on high lev­els of ven­ti­la­tion to dry out the wa­ter it was as­sumed would get into your house. It’s pos­si­ble to get draught ex­clu­sion done pro­fes­sion­ally for be­tween £75-£250. The Energy Sav­ing Trust has a lot of help­ful ad­vice on DIY draught-proof­ing.

Heat­ing the home

Once the warm air in the build­ing is pre­vented from get­ting out and cold air from get­ting in, the fi­nal steps are to choose the most ef­fi­cient energy source, dis­tri­bu­tion sys­tem and con­trols.

A con­ven­tional gas con­dens­ing boiler will cost about £2,500 in­stalled (in­clud­ing ad­di­tional ther­mo­static ra­di­a­tor valves), and the EST website quotes sav­ing of up to £320 a year if the boiler re­placed was band G and only 70 per cent ef­fi­cient.

re­new­able heat sys­tems are de­sir­able if you want to be green, but only re­ally be­come cost-ef­fec­tive once you’ve got the build­ing work­ing ef­fi­ciently. Fu­els range from biomass to the var­i­ous forms of re­new­able elec­tric­ity (gen­er­ated on site through things like so­lar pan­els, wind tur­bines, or run­ning wa­ter, for those near streams or rivers, or im­ported).

Heat sources start with wood boil­ers and stoves, us­ing logs, wood chips, or pel­lets. They’re quite con­ven­tional in the way they work, and more fea­si­ble if you have the space and the time to run them. An au­to­mat­i­cally fed pel­let boiler for an av­er­age home costs be­tween £9,000 and £21,000.

heat pumps might cost be­tween £7,000 and £11,000. they work like a fridge in re­verse, tak­ing heat from the air or the ground and pump­ing it into your house, us­ing maybe 1Kw of elec­tric­ity to pro­vide 4Kw of heat. they’re more au­to­matic in the way they work, and since they don’t need stor­age space for the fuel, are bet­ter suited to ur­ban lo­ca­tions. Most will sound about the same as a fridge run­ning, but is­sues of noise needs to be con­sid­ered in ur­ban lo­ca­tions.

Ther­mal stores – typ­i­cally a big wa­ter tank – can use a sin­gle re­new­able energy source or sev­eral. Sys­tems can com­bine a gas or oil boiler with so­lar ther­mal, PV, wood-fired range cooker, wind, and a ground source heat pump. Costs will vary ac­cord­ing to the tech­nolo­gies be­ing used.

A heat­ing sys­tem isn’t some­thing that you gen­er­ally in­stall your­self, par­tic­u­larly if gas or elec­tric­ity are in­volved, and the build­ing reg­u­la­tions re­quire that the work be done by a com­pe­tent per­son. To find reg­is­tered in­stall­ers try the Com­pe­tent Per­sons Reg­is­ter. Be sure the in­stall­ers are MCS Cer­ti­fied, and if us­ing gas or oil, are reg­is­tered with GAS SAFE or OFTEC.

The right heat­ing sys­tem for you and your house de­pends on the size and con­struc­tion of the prop­erty, how you live in it and your bud­get.

Gen­er­ally, a ther­mally mas­sive build­ing, such as a con­verted barn or Ge­or­gian stone house, that’s in use through­out the day, is best served by a sys­tem that’s on all the time. A good op­tion will be a heat pump pow­ered by re­new­able elec­tric­ity dis­tribut­ing to un­der­floor heat­ing and with smart op­ti­mised con­trols. At the op­po­site end of the spec­trum, a ther­mally light­weight build­ing will heat up and cool down quickly. If the use is very in­ter­mit­tent, a wood-burn­ing stove, heat­ing up the air only might be best.

the website en­er­gysav­ of­fers fur­ther in­for­ma­tion on boiler re­place­ment, re­new­able energy, home in­su­la­tion, and energy ef­fi­ciency. see ex­am­ples of energy-ef­fi­cient homes and find de­tails of open house events at su­per­

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