feat: social value calculations

app/components/Dashboard/Cards/WhatDifference.tsx

@@ -1,13 +1,21 @@
-
+import { Household } from "@/app/models/Household";
 import { Drawer } from "../../ui/Drawer";
 import GraphCard from "../../ui/GraphCard"
 
+type CardsProps = {
+  household: Household;
+}
+
 type CardProps = {
   title: string;
   figure?: string;
   subfigure?: string 
 }
 
+type WhatDifferenceProps = {
+  data: Household;
+}
+
 const Card: React.FC<React.PropsWithChildren<CardProps>> = ({ title, figure, subfigure, children }) => (
   <div className="flex flex-col w-1/5">
     <p className="text-lg font-semibold mb-0">{title}</p>
@@ -27,43 +35,43 @@ const Highlight: React.FC<React.PropsWithChildren> = ({ children }) => (
   <span className="text-green-500 font-semibold">{children}</span>
 )
 
-const Cards = () => (
+const Cards: React.FC<CardsProps> = ({ household }) => (
   <div className="flex flex-wrap gap-6">
-    <Card title="Money saved" figure="£30,000">
-      <p>On housing costs over 10 years, compared to conventional ownership</p>
+    <Card title="Money saved" figure={`£${Math.round(household.socialValue.moneySaved).toLocaleString()}`}>
+      <p>If Fairhold Land Purchase, on housing costs over 10 years compared to conventional ownership</p>
     </Card>
     <Card title="Community wealth">
       <p>
         Every 10 years the house would contribute{" "}
-        <Highlight>£120,000</Highlight> to community infrastructure and services
+        <Highlight>£{Math.round(household.socialValue.communityWealthDecade).toLocaleString()}</Highlight> to community infrastructure and services
       </p>
     </Card>
-    <Card title="Embodied carbon savings" figure="40 TCO₂e">
+    <Card title="Embodied carbon savings" figure={`${household.socialValue.embodiedCarbonSavings} TCO₂e`}>
       <p>If new build, compared to typical development</p>
     </Card>
-    <Card title="Energy savings" figure="£500" subfigure="per year">
+    <Card title="Energy savings" figure={`£${Math.round(household.socialValue.savingsEnergyPoundsYearly).toLocaleString()}`} subfigure="per year">
       <p>Every year, if new build or retrofitted</p>
     </Card>
-    <Card title="Savings to NHS" figure="£2,000">
+    <Card title="Savings to NHS" figure={`£${Math.round(household.socialValue.savingsToNHSPerHeadYearly).toLocaleString()}`}>
       <p>per person, per year of a healthy, well-maintained home</p>
     </Card>
     <Card title="Local economy">
-      <p>If a new build, the home would add <Highlight>£200,000</Highlight> to the local economy, and <Highlight>£3,000</Highlight> every year, supporting <Highlight>3.6</Highlight> jobs in total</p>
+      <p>If new build, the home would add <Highlight>£{Math.round(household.property.newBuildPrice).toLocaleString()}</Highlight> to the local economy, and <Highlight>£{Math.round(household.lifetime.lifetimeData[0].maintenanceCost[household.property.maintenanceLevel]).toLocaleString()}</Highlight> every year, supporting <Highlight>{household.socialValue.localJobs}</Highlight> jobs in total</p>
     </Card>
-    <Card title="Annual carbon savings" figure="3 TCO₂e">
-      <p>If new build, compared to average home</p>
+    <Card title="Annual carbon savings" figure={`${household.socialValue.operationalCarbonSavingsYearly} TCO₂e`}>
+      <p>If new build or retrofit, compared to average home</p>
     </Card>
   </div>
 )
 
-export const WhatDifference: React.FC = () => {
+export const WhatDifference: React.FC<WhatDifferenceProps> = ({ data }) => {
   return (
     <GraphCard 
       title="What difference would Fairhold make to me, my community, and the world?"
       subtitle="Social, environmental and economic impacts"  
     >
       <div className="flex flex-col h-full w-3/4 justify-between">
-        <Cards />
+        <Cards household={data}/>
         <Drawer
           buttonTitle="Find out more about how we estimated these"
           title="How we estimated these figures"

app/components/ui/Dashboard.tsx

@@ -41,7 +41,7 @@ const Dashboard: React.FC<DashboardProps> = ({ inputData, processedData }) => {
         <HowMuchPerMonth processedData={processedData} />
         <CostOverTime processedData={processedData} />
         <ResaleValue data={processedData} />
-        <WhatDifference />
+        <WhatDifference data={processedData}/>
         <WhatWouldYouChoose />
       </div>
       <Carousel

app/models/Household.ts

@@ -9,6 +9,7 @@ import { ForecastParameters } from "./ForecastParameters";
 import { socialRentAdjustmentTypes } from "../data/socialRentAdjustmentsRepo";
 import { Lifetime, LifetimeParams } from "./Lifetime"; 
 import { KWH_M2_YR_EXISTING_BUILDS, KWH_M2_YR_NEWBUILDS_RETROFIT } from "./constants" ;
+import { SocialValue } from "./SocialValue";
 
 const HEADS_PER_HOUSEHOLD = 2.4;
 
@@ -44,6 +45,7 @@ export class Household {
     billExistingBuildYearly: number;
     billNewBuildOrRetrofitYearly: number;
   }
+  public socialValue: SocialValue;
 
   constructor(params: ConstructorParams) {
     this.incomePerPersonYearly = params.incomePerPersonYearly;
@@ -54,6 +56,7 @@ export class Household {
     this.gasDemand = this.calculateGasDemand(params)
     this.tenure = this.calculateTenures(params);
     this.lifetime = this.calculateLifetime(params);
+    this.socialValue = this.calculateSocialValue();
   }
 
   private calculateTenures({
@@ -165,4 +168,11 @@ export class Household {
       const kwhYearly = params.property.size * KWH_M2_YR_NEWBUILDS_RETROFIT[params.property.houseType]
       return kwhYearly
     }
+
+    private calculateSocialValue() {
+      return new SocialValue({
+        household: this
+      })
+    }
+
   }

app/models/SocialValue.test.ts

@@ -0,0 +1,27 @@
+import { SocialValue } from "./SocialValue";
+import { createTestHousehold } from "./testHelpers";
+
+const household = createTestHousehold();
+const socialValue = household.socialValue
+describe('Social Value', () => {
+})
+    it("can be instantiated", () => {
+        expect(socialValue).toBeInstanceOf(SocialValue)
+    })
+
+    it("calculates money saved", () => {
+        expect(socialValue.moneySaved).toBeCloseTo(184266.707)
+    })
+    it("calculates money to community", () => {
+        expect(socialValue.communityWealthDecade).toBeCloseTo(5917.45)
+    })
+    it("calculates energy bill savings", () => {
+        expect(socialValue.savingsEnergyPoundsYearly).toBeCloseTo(554.4)
+    })
+    it("calculates amount generated for local jobs", () => {
+        expect(socialValue.localJobs).toBeCloseTo(3.2)
+    })
+    it("calculates operational carbon savings", () => {
+        expect(socialValue.operationalCarbonSavingsYearly).toBeCloseTo(1.465)
+    })
+

app/models/SocialValue.ts

@@ -0,0 +1,64 @@
+import { Household } from "./Household"
+import { KG_CO2_PER_KWH, NHS_SAVINGS_PER_HEAD_PER_YEAR, FTE_SPEND } from "./constants";
+
+type ConstructorParams = {
+    household: Household};
+
+export class SocialValue {
+    public moneySaved: number;
+    public communityWealthDecade: number;
+    public embodiedCarbonSavings: number;
+    public savingsEnergyPoundsYearly: number;
+    public savingsToNHSPerHeadYearly: number;
+    public localJobs: number;
+    public operationalCarbonSavingsYearly: number;
+
+    constructor(params: ConstructorParams) {
+        this.moneySaved = this.calculateMoneySavedFHLP(params);
+        this.communityWealthDecade = this.calculateCommunityWealth(params);
+        this.embodiedCarbonSavings = 31.89; // TODO: update figures, not placing in constants.ts because it's placeholder; static number comparing average brick & block emissions vs. timber on slab
+        this.savingsEnergyPoundsYearly = this.calculateSavingsEnergyPoundsYearly(params);
+        this.savingsToNHSPerHeadYearly = NHS_SAVINGS_PER_HEAD_PER_YEAR
+        this.localJobs = this.calculateLocalJobsSupported(params);
+        this.operationalCarbonSavingsYearly = this.calculateCarbonSavingsYearly(params);
+    }
+
+    private calculateMoneySavedFHLP(params: ConstructorParams) {
+        let marketPurchaseTotal = 0;
+        let fairholdLandPurchaseTotal = 0;
+        const lifetime = params.household.lifetime.lifetimeData
+        for (let i = 0; i < 10; i++) { // TODO: should this include bills? TODO: do we want to show 10 years only? using 10 here because designs showed savings over 10 year period, not lifetime
+            marketPurchaseTotal += (lifetime[i].marketLandMortgageYearly + lifetime[i].newbuildHouseMortgageYearly)
+            fairholdLandPurchaseTotal += (lifetime[i].fairholdLandMortgageYearly + lifetime[i].depreciatedHouseMortgageYearly)
+        }
+        const moneySaved = marketPurchaseTotal - fairholdLandPurchaseTotal
+        return moneySaved;
+    }
+    private calculateCommunityWealth(params: ConstructorParams) {
+        const lifetime = params.household.lifetime.lifetimeData
+        let communityWealth = 0
+        for (let i = 0; i < 10; i++) { // TODO: decide on time period
+            communityWealth += lifetime[i].fairholdLandRentYearly
+        }
+        return communityWealth;
+    }
+    private calculateSavingsEnergyPoundsYearly(params: ConstructorParams) {
+        const gasBillSavings = params.household.gasDemand.billExistingBuildYearly - params.household.gasDemand.billNewBuildOrRetrofitYearly
+        return gasBillSavings;
+    }
+    // private calculateLocalEconomyBoost(params) {}
+    private calculateCarbonSavingsYearly(params: ConstructorParams) {
+        const operationalEmissionsExistingBuild = KG_CO2_PER_KWH * params.household.gasDemand.kwhExistingBuildYearly
+        const operationalEmissionsNewBuildOrRetrofit = KG_CO2_PER_KWH * params.household.gasDemand.kwhNewBuildOrRetrofitYearly
+        const operationalEmissionsSavedTCo2e = (operationalEmissionsExistingBuild - operationalEmissionsNewBuildOrRetrofit) / 1000
+        return operationalEmissionsSavedTCo2e
+    }
+
+    private calculateLocalJobsSupported(params: ConstructorParams) {
+        const maintenanceLevel = params.household.property.maintenanceLevel
+        const totalSpend = params.household.property.newBuildPrice + params.household.lifetime.lifetimeData[0].maintenanceCost[maintenanceLevel]
+        let jobsSupported = totalSpend / FTE_SPEND
+        jobsSupported = parseFloat(jobsSupported.toFixed(1));
+        return jobsSupported
+    }
+}

app/models/constants.ts

@@ -177,4 +177,10 @@ export const KWH_M2_YR_NEWBUILDS_RETROFIT = {
   T: 20,
   S: 51,
   D: 55
-}
+}
+
+export const KG_CO2_PER_KWH = 0.185 // from Carbon Independent https://www.carbonindependent.org/15.html#:~:text=Natural%20gas&text=Older%20gas%20meters%20measure%20gas,kg%20%2F%20kWh%20%5B9%5D%20.
+
+export const NHS_SAVINGS_PER_HEAD_PER_YEAR = 24.78 // from BRE report in 2021, NHS first-year care costs due to poor housing in England individualised
+
+export const FTE_SPEND = 60000